To me this is one of the better things about combat in Dwarf Fortress and one of my least favorite things about most rule sets. It doesn't matter how "high level" you are; outside of specific edge cases a ridiculous number of opponents all landing hits simultaneously ought to do anyone in. Unfortunately most rule sets seem to stop at "lol high AC" with little to no nuance.
Considering a crit always hits in a lot of systems, I don't see how a swarm of weak enemies couldn't overwhelm high level players given enough numbers.
