Brawl is a much higher power format than Alchemy itself is, and from what has been printed into Brawl recently, that's only going to become increasingly true. Therefore it's an issue for the format that some cards are arbitrarily made worse because they happened to break Alchemy when they were never an issue in Brawl itself, or were an issue in Brawl so long ago that they wouldn't be now.

Leyline of Resonance, Cori-Steel Cutter, Dragon's Rage Channeler and many, many others, would be complete nonissues in Brawl as printed in paper, or at least wouldn't be power outliers at all. I happen to play a lot of red so those are the best examples that come to mind for me but I have no doubt there's examples in all of the colours.

I'd understand keeping buffed cards like Sorcerer Class as rebalanced versions, and obviously things like Nadu shouldn't be returned to their printed state, but there's over 200 cards rebalanced, and not all of them need to be rebalanced in Brawl, including while a rebalanced version is in Alchemy. They're different formats, it's okay for one to use one version and another to use another. I'm not suggesting more than two, but just one paper and one rebalanced.