Yes, yes there are.
It's called 4chan.
There was a UK website when similar stories but with no moderation and no forum before I found this place. Think it shut down though as the name eludes me.
Choice of Games has a very welcoming community that's open to all opinions and perspectives. I suggest giving them a look.
I've heard myadventuregame.com is pretty similar
I do believe that https://www.starcatcher.org/index.php is a CYOA website, but it is just for kids.