It’s who left that matters. We lost a TON of tech people. People with experience and knowledge in the field.

You aren't kidding. The tech knowledge of the average redditor has been dropping for years as the site became increasingly mainstream but it cratered after the API change. It's very amusing to read through a thread about lemmy in r/technology though. According to the average redditor picking an instance and then clicking the "communities" section to subscribe to comms you're interested in is the most complicated thing they've ever encountered in their lives. It's silly. Lemmy took about as much time for me to get the hang of as reddit did when I first joined in 2011. A few days, maybe a week tops... And that includes the time I spent test-driving different front ends and apps before settling on a desktop/mobile combo of Alexandrite and Voyager.

Sure, understanding how federation works may take awhile but you really don't need to know much about any of that to get setup and start participating as a user.