While I’m not a sociologist, it seems to me that the mania furries have for grooming and recruiting comes from their roots as a gay subculture. My personal experience was they just love the idea of “converting” straight normals and besides, they need as many recruits as they can get; when everyone’s a weirdo then no one is, right?
Seriously - and my snark aside - they really seem to get off on the idea of converting people and they really have this mania for needing everyone to like what they like, and join in on what they consider fun. I’ve known model railroaders, hot rodders, surfers, gamers, model ship builders, trekkies, and all sorts of others and nobody else has had that ‘you gotta join us and your a sad pathetic person if you dont’ contempt that furries have for normals.