See, I don’t think that 20 does make up for that 1, any more than your 20 on an attack roll lets me roll damage on my 1.
The party isn’t some cohesive, singular unit that catches or avoids attention based on some average of the total behaviour. It’s instead a cloud of actors that are only as strong as its weakest member.
Like, if they were 4 kids sneaking cookies from the cookie jar, and the youngest knocked the jar off the counter, it really doesn’t matter how quiet the other 3 were, the shattering of the jar is going to get them all caught.
No, it’s also better if you want an internally consistent system built on top of sensible principles. Or a system with reliable baseline for power scaling. Or if you want to invite an optimizer or a newbie to your table.
It’s not a “tactical combat RPG”. That’s a wild misconception propagated by both tactical combat fans and people who have looked over the hedge and been scared away by somethings being different. It is, instead, a well crafted systemic RPG, designed with reliability at its centre.
Reliability enables tactical combat, which is why TC fans flocked to the system, but it enables a hell of a lot more, too.
It’s also better if you want a steady stream of new content without paying Hasbro or relying on randos.