Like what Pat said. The people who were drawn to the ASMB in the first place were united by common interest in some weird programming. It was a broad range of people who got together because we all liked one niche thing. And where we were all weird for liking weird shit, it was easier to get along and meet folks and find more shared interests.
On top of that, the original ASMB was built as a real community. SwimBuddha running shop at first, making threads about going to the vending machine and how he'd buy the first person who replied a candy bar. SwimTorrent taking user ideas for polls on the site. The team actually sharing what users were saying on TV. And then you had showrunners and talent like Andy Merrill making the SwimBuddha eats poop thread, and Adam and Matt from Sealab creating the character MCHeshPants420 and trolling the boards before they dropped the episode "Dearly Beloved Seed." From the community the channel actually provided, it encouraged people to have fun and be weird and open.
And from there it just grew. After chatting on the boards about topics a and b, it was easy to go into topics c and d and so on off the boards to online chat, and from online to real life meeting. It was super comfortable because these were already friends that we knew from a community that valued us all.
And UEMB here is an extension of that, because even though the channel left us, the community and friendships were still there and there was a want to spread that feeling again.
Or maybe we're just all fucking loonies. I dunno.