This seemed like an extremely odd conversation. Two items come to mind.
First, the idea that Mastodon is “complicated” comes from people who want to keep everybody on the big-corporate networks. Journalists like to spread that, because they barely tolerate Twitter, because they’ve been shamed after not covering important stories too many times, so they absolutely don’t want to care about a world where you can follow someone who might be posting videos, pictures, or book reviews. But except for weird “why do I not see real-time updates?” edge cases, it’s not particularly difficult to figure out.
Yes, you need to pick a server from an indistinguishable mass of options. Has nobody ever bought insurance, before? Mustard? “Oh, there are so many choices, and I can’t tell which one, so I guess I’ll just skip it” isn’t how any part of the world works, except for Free Software.
Then, the design decisions. Before I stopped checking in, my Twitter timeline was invariably one-in-ten posts that were quote-tweets of some creep mouthing off in sexist and/or racist ways, with the tweet being “you know what to do,” looking to get that person reported until banned. Those people learned that behavior from organized harassment campaigns, where the goals were anything from direct harassment, to provoking a ban, to doxxing them for harassment off Twitter. But it’s not really tit-for-tat, because quote-tweets boost attention for the creep, so once they appeal the ban, the algorithm recognizes them as driving more engagement.
That doesn’t even get into the structural issues of quoting an entirely normal thing with a supportive (or unsupportive) comment, and then the original tweet gets deleted, so it’s now just a tweet that says “check this out” or the ever-popular “This”…
Getting back to the original question, though, nothing is going to replace Twitter (including modern Twitter), because Twitter managed to attract CEOs and politicians, who drew in journalists. Twitter was credible in a way that I don’t think that anybody else has a chance of doing in the near term. And that’s probably OK…