If the party survives, then what is the issue here? Besides a lot of healers DON'T play SCH that way or even have ED on their hotbar and will overheal anyway.

Who cares if it's balanced around? If the party isn't dying then again what's the issue if a player is trying to maximize damage? Obviously a smart player wouldn't be doing that if the party is taking a lot of damage and won't survive. There is nothing wrong about spending excess resources during downtime, which is good design in my opinion.

Besides, if your damage output becomes an expectation and you are being excluded or harassed over it, there's a system in place to penalize that so it's a moot point.