It will never be mainstream for the fact its a confusing mess for most people to figure out, let alone tech literate ones. Facebooks involvement or not.

and theres your problem, looking at instances, its not a normal thing you need to do or ever had to do on any other similar website reddit would have never taken off if it where instanced like lemmy for example

how many instances did you look at, how often where you greeted with “choose an instance” lemmy is not as easy as techys think it is

As much as people may not like to hear it Ease of use from being one centralized platform is a big factor

Just login and be done with it