I'm just going to say it. I don't have any empirical evidence.
One of the biggest reasons Bluesky may have been "the choice" is because they have quote-posts natively.
And what that boils down to is responsiveness to the userbase. That's really what Mastodon needs to get better at. If people start to feel that, even slowly, the product is getting better for all, then it will succeed. If people think it will never change, then it will never reach its full potential for users.