I've accidentally ghosted people in the past despite wanting to reply to them and at times even saying I'd have a reply coming soon simply because I have a very high intensity job in the real world that can sometimes take up a lot of my time, focus and mental energy. There've been times where all my thoughts are focused on that because they have to be in order to do my work well and not cost lives IRL, and that comes at the detriment of remembering other things that just aren't as important. Add in on top of that the other day to day stresses and strains of just existing and sometimes things slip. I can't recall ever ghosting someone to be malicious, and I've never gotten the sense that anyone ghosting me did it maliciously either - and it's happened a lot in over 15 years of roleplaying. So no, personally I don't think people should be punished for ghosting.
My advice to anyone struggling with being ghosted would be to take a step back and consider what could be going on for the person ghosting you. It's natural to worry that we did something wrong or aren't good enough, but there are lots of other possibilities that people have mentioned here. Maybe they're stressed, anxious, busy, dealing with grief, feeling unwell, in a creative funk, needing a break from their day to day life, out with friends, dealing with a crisis, having mental health issues, the list goes on. If the ghosting keeps happening and keeps annoying you, ask yourself why it bothers you so much, then weigh up the pros and cons of letting the situation continue as it is. If the pros of waiting for the person and potentially continuing the RP outweigh the cons, be patient and wait for them, and in the meantime find a new RP to start with someone else. If the cons outweigh the positives, move on gracefully and leave the RP behind.