Telling people to "just use Firefish" is a common thing that comes up when people talk about this, but it's not really a solution at all with where we're currently at. (this isn't aimed at you, by the way, just addressing this specific point)
Whether we like it or not, Mastodon is by far the biggest player in the microblogging space (8M accounts on Mastodon vs 499K on Misskey at #2. with Mastodon being 77.9% of the entire Fediverse!), and it is going to be what the vast majority of people are using, simply due to word of mouth or mindshare. On these sorts of platforms, many features depend on the people you're posting to also experiencing the same features you are. Quote posts are a very popular topic that's requested for various reasons on Mastodon, but while the 3rd party apps and other microblog platforms have these implemented, it doesn't matter if 80%+ of your followers are using Mastodon, because they won't see the post as you intend for them to see it.
Furthermore, as we know, the "culture" of Mastodon is of the Fediverse at large, using a different platform isn't going to fix this issue - your community is what you make of it depending on your instance really, but fact of the matter is, most people are going to be drawn to the simpler general instances "where everyone is at", which is going to be the big Mastodon instances. Trying to divert those people to other platforms isn't going to work, because they don't understand how all this works, so good first impressions need to be made on Mastodon, and unfortunately due to the culture of Mastodon attracting a certain type of crowd and no mass migrations to "Eternal September" the culture, especially since Threads now exists, this is going to be a very hard barrier to overcome.
Whenever I've talked to people about Mastodon outside of the tech-savvy spaces, most people just see Mastodon as an app and there are "people on Mastodon", attempting to try and introduce people to all these different platforms and how you can still talk to everyone in places unfortunately just makes their head explode, as they're not used to the open web due to how it evolved after the rise of Facebook.
Mastodon is stuck between a rock and a hard place, where it wants to make decentralisation the norm by attracting as many people as possible, while still keeping its general culture in place and not wanting to turn into "another Twitter" which usually ends up being filled with hot takes and people dunking on people for entertainment - but unfortunately, this is how people consume social media now, it's all about content.