[dspillett]

You might be happier in life if, having decided that you didn't like how things were done there, you moved on and got on with things elsewhere, rather than moving on but still being bitter and complainy about it to this very day.

[matheusmoreira]

It's not bitterness, it's anger. It can be a rather enjoyable and cathartic emotion, especially when one is confronting perceived wrongs.

Another benefit of sharing experiences, especially negative ones: it can help others. Maybe there are people on this site who aren't yet aware that stack exchange embraced deletionism. I certainly wasn't, wouldn't have contributed otherwise. If I help even one person realize this, it was worth it. That realization could prevent them from having their work closed down and deleted before they had even finished writing it.