There’s certainly some marketing (“Check out our new paper”, “My lab is hiring”, etc), but it’s not particularly top-down; everybody does it to some extent. It’s also mixed in with actual scientific discussion, lab “hacks”, and some silly banter/blowing off steam. All in all, it’s been pretty helpful for me careerwise. I think I’ve gotten more useful advice about grant writing and papers to read than many more formal mentorship arrangements.

There are a few “blue checks”, but they’re mostly a) early adopters or b) people with some kind of public presence. As far as I can tell, neither I nor most others care about the checkmark per se. I talked about my research (twice!) with John Carmack and it was cool to know that it was really the Doom Guy, but I think I probably would have engaged with anybody equally curious about my work.