Why a legacy mode would do this game justice

I'm pretty sure that keystone runes, and those top tier mastery runes from a few seasons ago are the main reason why League has so much damage. That passive that appears under your splash image instantly increased the power creep of the game by an extra passive. Now, every rune is a passive of some kind, which to my perception, is undermining the unique abilities of champion kits. Then you have keystones like electrocute that allow you to make 100-0 combos.

If we had, say, the masteries and runes from 2014, League wouldn't be as snowbally as it is today. Games would actually last, too, and not end in 25 minutes or less.

Any thoughts?