You can think that and the rules make that possible. I don't think that is actually what Magi think of as legacies.I think they consider apprentices and students to be legacies. I don't think that the entire Order acts like they are Bonisagus magi.I don't think that they are obsessed with theoretical knowledge (highest possible Art) and I don't think they are keen on sharing their knowledge. And I don't think that these high quality books are being traded. People are letting you study in their library for compensation.
Between Ex Misc traditions, Mystery Houses, and Mystery Cults, half the Order is in some kind of secretive organization with oddball magic. Yes, game mechanics let a Merinita Archmage write a book on vanilla Imaginem with no faerie mysteries involved, but why would they? The Faerie mysteries are what they are about. And mystery cults don't circulate their knowledge. That's what makes them Mystery Cults.
Do you think Tytalus or Flambeau Magi are generally gonna go "woah, that dude's clearly the best, look at this book he wrote!". Not to mention there isn't a game mechanic objective standard in character. Is Lord of the Rings actually the best fantasy novel if there were game mechanics? It's clearly good, influential, and highly regarded. But someone coming a long and publishing a "better" book doesn't make them likely to displace Tolkien.
And, fundamentally, I don't think the players' obsession with maximum Art scores is actually how wizards would work. There's so many practical things to do with Magic that are more impressive than grinding out season after season of incremental progress. And in character, without mechanics, who is going to know you are now 42 instead of 40 if fame is actually what you are after? New spells, magic items, weird personal achievements, smiting dragons, and all kinds of applied magic is how most wizards will evaluate someone's power and success. Unless you are in a Bonisagus mindset, you get the high art to do the practical things. Not for the sake of having the high art. Even the Bonisagus Folio favors lab texts over tractatus.