It's the first time I hear of it, but https://bigbluebutton.org/ times out and it doesn't seem to be packaged for Arch Linux (not even AUR) so it doesn't look like it's very well known?
Yes ! We use this one at work (150 employees) and it's really good. You can do only audio or audio + video. It supports recordings and is self hosted. Give it a try !
It's really lacking in Linux distributions
You are right. 64 bit Ubuntu 16.04 alone is supported. It allows them to focus and ship faster updates.