I'm mostly focused on going to a place and seeing lots of posts and comments. Behind the scenes, the tech that powers it? While I'm interested in it from a tech stand point, most regular people just don't care.

you're right that a large majority of people do not care, but this mentality will begin to change at some point. Also, the entire point of this is that it doesn't matter where the users are, because they can still join the same communities. Now, there are obviously a lot of things that need to improve in lemmy to make it more usable, but federation isn't one of them. The ActivityPub protocol is simple, yet powerful and relatively scalable.

Email works, or used to until giant corporations consolidated hundreds of small providers into a handful. I don't know why it wouldn't work for this.

Sure, the average user doesn't care how it works. That doesn't mean they can't use it as intended anyway.

Yeah, combine that with folks not understanding while registering that you can still see things from other servers while registering. They may kick the big one thinking it means they'll see the most content.