This would completely destroy the purpouse of a ranking system. Not only would any ELO from 1k-1.8k become the new ELO hell with half the community selling out and jumping up the lowbies to near if not to platinum by pure chance. It would just be a more glorified draft mode.
Ruining the allure to buy riot points, no longer will that legendary you have hold any merit when 90% of the community got it for free. With less people buying RP we stop seeing patching, Old models are never revamped. Sion never gets removed from the game. Truly hell on earth.