I agree to an extent, but usability is not a sufficient condition for mass adoption. I think Lemmy for end users is just as usable as Reddit was, at least for me it is. But people don't want to leave their communities.

That's why personally I have a Discord still. There are too many communities I am an active part of on there to abandon Discord outright. Plus all of my friends and family are on there, and I've already approached some them about switching and they all have said the same thing I just did.

I wasn't ever super invested in Reddit, so it was easy for me to abandon it for Lemmy, and I vastly prefer the communities here. Discord though is a different story for now, unfortunately.