It exists because people are constantly flooded by a torrent of pressure to have children by society, and this is a place for a little catharsis and relief. Relief that there are a small number of people that won’t pressure you into doing something you don’t want to do. It’s a place for like-minded people to blow off steam.
I don’t personally come to this or similar communities, even though I don’t plan on having kids. I understand why it exists though.