Even if old runes were free they would be kinda problematic anyways.
Like imagine you're a new player and you need to go do your 30 slot rune page and you can put like 100 diffrent effects in each slot.
Do i want to respawn faster?
Do i want to passively generate gold more gold per minute?
Do i want crit chance?
Do i want armor?
Maybe i go movespeed?
Maybe i want more exp?
Maybe...
Thank god i started playing after that shit already got removed.