Sure, but all of this basically comes down to poor marketing. It's not an inherent problem with the technology or with the concept of federation.
It shouldn't be surprising either given that Mastodon is a niche platform developed largely as a volunteer effort. The reason people advocating Mastodon tend to focus on stuff like on the flaws of the centralized social media is because that's what matters to them. We see pretty much the same thing happening with Linux, and many other open source projects.
This is the point I was making above, BlueSky has a professional marketing team that understands how to sell their product to the general public. That's the main reason BlueSky is gaining users at a faster rate.
Regarding the Gmail problem, it's true that we could end up with one major instance most people are on. I don't see that as a huge issue in practice since you can still choose use different instances. That's a fundamentally better situation to be in.
For example, I don't use Gmail and I run my own personal Mastodon instance using masto.host, this doesn't stop me communicating with people on Gmail or major Mastodon instances like mastodon.social.
Sure, if a big instance started to dominate the fediverse it would be a form of centralization. However, the protocol being designed with federation in mind makes it much easier for people to migrate from that instance if it becomes a bad actor.
Going back to the original point though, I do think that fediverse could be marketed better in a way that would appeal to more people. Since we agree that federation is a desirable feature, the focus should be on figuring out how to explain it to people in a sensible way.