Would Overheal be a more popular choice if the cap wasn't so low?
I was thinking about playing soraka and was like hey maybe the adc should take overheal, and wow I forgot that rune even existed. So I looked at the numbers and it gives 300% hp from other champ's heals-maybe it could be good with a healing support! But the cap is only 10+10% of max hp...unless a heal is for less than 3+3.3% of an adc's max health, which I feel like is unlikely, the cap is going to prevent it from working fully.
Why is there a cap at all? It would be super cool if it was unlimited or was big enough that you could actually pump at least a single heal into an adc, preferably multiple heals. I like the idea of increasing the cap because you wouldn't necessarily feel like you're wasting abilities when you heal someone with overheal.
or just because you never reach full health in a fight after taking initial damage, that rune slot of yours might aswell be empty.