As someone who's quite new here (only joined a few months ago) I think a major hurdle for this place is the account approval system. With most places on the internet these days it takes mere seconds to set up an account and get chatting, but here it takes a bit longer since you need to be reviewed and approved first which can take days (took about half a week for me iirc?) and in an age where people want everything NOW NOW NOW that's sadly to this forum's detriment when it comes to getting new members.
That and the interface itself has a very "old internet" look with the grays and 2000's design which could make newcomers think "Oh, this must be a dead site that's still left up for some reason" and not engage any further.
Now, I for one don't mind these things (I'll take it over the social media vomit currently infesting society any day), but put yourself in the perspective of someone looking around for a place to discuss snakes and it gets a little more obvious why this forum is sadly dwindling... Even in my relatively short time here the lack of activity has been glaringly apparent.