Not exactly, no. Year One was an origin story that replaced an earlier story, throwing it out the window. I've never read it but isn't Joker's Five Way Revenge largely self contained and not particularly reliant on continuity? And it isn't just the comics that makes the character cool. Cartoons and movies are outside the 70+ years comic continuity and are more popular. Sure they take inspiration from and even loosely adapt some of the comic stories, but that just shows that it's the stories that are most important, not the continuity they are in.
I find that a pretty flimsy argument. Of course every story is it's own continuity, and of course every character in that story will fit in that continuity, that's just how stories are done. That's just the fact characters must work in their world, that plots have logical consistency or they fall apart. But that you can have so many popular characters come from other continuities, that a character like Batman can work in so many continuities shows that stories are the more important factor.Well, not really. Because, while Harley Quinn and Carrie Kelly may not have been created in the main DC continuity, they were still products of continuity. They were born out of the continuities of their respective worlds: the DCAU for Harley and the Dark Knight Returns continuity for Carrie. Carrie's story doesn't make sense without the set up of DKR. She doesn't make sense as a character without that world around her, where Batman has long retired and Gotham has turned into a cesspool. The same thing goes for Harley. And it should also say something how Harley's popularity spurred them to bring her into the main continuity, but at the same time, DCAU Harley is not the same as main DCU Harley. Those are two different characters and the realities of the DCU have made Harley evolve into who she is today.
I never said that he should be in his 20s. He should start there in his early career, but I would peg him to be in his 30s now. But outside of other continuities he should never grow old and retire. Batman Beyond is always set in the future, it should never become the default present.Plus, even if you don't think Bruce should be north of 50, that doesn't mean he should be in his 20s either. Like, honestly, I don't buy a Bruce Wayne in his 20s. The maturity, authority, and reputation the character demands requires him to be in his late 30s at least. You don't build up a reputation as "the goddamn Batman" when you're like 25. You have that reputation when you have some years under your belt.