This was an interesting list of anecdotes and variances in what others consider 'good' for an RP and environment. My own standards put me in a 51% Discord / 49% Forum disposition. It was also interesting to see someone to say that chatters are younger. I'm gonna date myself and say I'm from the generation that caused the bloom of chat rooms, and that most RP back then was chatting. We were looking to recreate the table-top gaming environment and pace in an online venue. It was truly interactive instead of dropping a letter in someone's mailbox for them to find tomorrow. Chat room games then broke off into the various messengers at the time. The online RP hobby was "I'm here for a couple hours. Let's do this as our focused activity together." This current forum style RP that dominates the online landscape looks like the evolution of the Livejournal collaborative novelists that were the weird ones, back then. I roleplayed online for about 8 years before I took a long break, and I never met a player back then who wanted to wait a day or two for a reply or thought +3 paragraphs was reasonable. Roleplaying was an activity rather than a semi-self-paced introvert hobby.
After my long break, I was dying of boredom at a bad job I was temporarily stuck in, and I wanted that focused interactive activity again. I couple other online artists tempted me onto Discord for roleplaying. It captured the feel of the RP I 'grew up' with back in the day. The two partners weren't quality, though, so I ended up venturing off to find others. When you Google looking for RP these days, it's basically all forums and static listings. I had a long period of adjustment to Craigslist-style ads looking for the "weird Livejournal" style of RP, but I accept that's what it mostly is, now. In between the cracks of forum partners, I have found good partners that also wanted to chat on Discord, and a couple even wanted to try it for the first time and said they really liked the active engagement in contrast to sitting alone and banging out paragraphs for a list of waiting partners on a forum. I'm not stuck at that boring job anymore, so my craving for focused interaction isn't my driving need, now.
Most of what I've been doing in the last few months is roleplaying in PMs on forums. That hybrid style is probably my least favorite option. It takes the slower static nature of a forum and blends it with the privacy of a chat to create... a situation that I find to be the most predisposed to ghosting. Yes, ghosting is a problem everywhere. I'll get to that in regards to Discord later, but I have had such a high percentage of forum partners that insisted on PMs turn out to be ghosters that I now really shy away from anyone that will only play in PMs. I also noticed that those who insist on PMs frequently have all their viewability settings shut down. It's a huge red flag. When I got started on forums, I really didn't want everyone reading my smutty posts. Between figuring out that that was probably rare, I also got over it and turned it into a tiny bit of an exhibitionist outlet. So, I definitely prefer either public forum threads or the intimacy of Discord. What I see as the secrecy of PMs is unattractive.
The best partners I've had since getting back into online RP were on Discord. The most creative, the most IC and OOCly engaging, and the longest. I think the active engagement helps to create a much more personable rapport, and that leads to better and longer stories. The longest forum threads I had were more mediocre and like the dinner rolls that filled up space between the chats I really enjoyed. I've also had some major disappointments on Discord, but that was just because of the quality of the stories and interactions. In almost two years, I've only had two people ever say Hi on Discord than never reply, like the OP mentioned. I don't find it to be a common problem. I've had fewer outright ghostings on Discord. I've had a lot of vague pauses that turned out to be permanent, but they were courteous enough to not leave me twiddling my thumbs. I think Discord, having many uses, is a place people will keep returning to even if they're not RPing, so it's a reminder to be polite. When you stop RPing, you just never go to that forum again. Out of sight out of mind. I'll also add to every other testimony to Discord's superior organization. The servers and channels are a godsend. I love it. It's so standard, with new partners, we just set everything up almost the same, and everyone knows what's going on. It's so great. As for post length, it's occasionally annoying, but it usually only catches me on intro posts or if I'm really GMing a big scene. It's a small price to pay for likely getting a response in 5 minutes.
As for the downsides of Discord, I'm not into all the forum styling, so it's not a problem. I'm an interactive designer, and my aesthetic/structural standards are on a professional level, which isn't gonna happen on RP forums with bb code, nor do I feel a need to do it with literature. Italic/bold is fine for me on Discord. I will say that trying to find partners on Discord is horrific. I've spent short periods of time on a lot of open RP servers, and it's just a mess. The forum RT style is far superior. The Discord ad channels are usually haphazard and inconsistent and just littered with red flags. I only ever felt like contacting one person I found on Discord, ever. It was weird, and he told me he didn't know how to play if we were sharing control of NPCs. ugh At least we only got 2 posts in before he had that realization.
Forums also have moods and moderation staff. Those are mixed bags. I do like some legal standards and not seeing underage ads everywhere. But other than that, my anxiety disorder has been triggered plenty when some mod speaks to me like forgetting a nuance of their unique policy that I read a year ago that isn't on the 4 other forums I frequent was me personally attacking them. No fear of that on Discord. It's just me and my partner. Also, the lack of being able to truly Block on xenForo forums is a huge problem. I'm tired of seeing staff everywhere reminding people of the Ignore function. It's not the same. My exact fear was realized here when someone I'd Ignored was posting crap on my profile. Another partner noticed and told me. With my career in UX, I have pretty high standards and strong opinions about prioritizing the users' experience on any platform. At least on Discord, the creep who sent me unsolicited nudes is blocked, and he can't ever see when I'm online, who I'm talking to, or leave bags of poo on my virtual front porch.
So, in the end, I'm old, but I adapted. I still prefer chatting and the venue that supports that the best, but longer forum posting also has its place, and I've grown accustomed to it. I'll keep looking for partners on forums, even if we move to Discord. And I'm gonna respect myself and stick to the 'public community' of threads or the intimacy of Discord, and avoid the secrecy of PMs.