I dunno if all pet sites are suffering because there are some that are super active (Flight Rising for example... can't believe it's been around for over three years already!) but some of the older ones seem to be dying or at least the users aren't as active on the forums. Even on FR a lot of users move their chats to Discord, Skype, Slack, etc. where they can talk about anything and everything and they can't get their actual accounts in trouble (aside from drama).
Maybe users just don't care for forums as much nowadays or maybe even chatting in general? It seems weird to me since so many people spend so much time online now.