This just seems like a lot of extra work and hoops to jump through to get this benefit
This isnt about optimization or turbo-power, this is more about cutting out near-unplayables (Aerie Mystics is not a card I saw hit the table and do anything, ever)
Cursed Mirror catches any relevant ETB effects upon hitting the battlefield, and it doesn't take much to get extra value out of it
Draw X cards, where X is the number of cards discarded this way
Furthermore, there's nothing wrong with running multiple types of Energy, but the more types that are run, the harder it may become to get the Energy you need at the right time
It has been eighteen years since Betrayers, and the number of cards that ignore the legend rule in some shape, form, or fashion has increased, with many of them being released in the past two years, in Modern Horizons 2, Kamigawa: Neon Dynasty, Strixhaven: School of Mages, Commander Legends: Battle for Baldurs Gate, The Lord of the Rings: Tales of Middle-earth, Wilds of Eldraine, Commander Masters, and Doctor Who Commander