For the millionth time, no, it does not. Abilities that drop enmity or reduce its generation exist, and good players will usually use them (plus, they are required in endgame content).
Good DPS will usually out-threat the bad ones even if they do use such abilities, tbh (whereas the bad ones have little/no reason to use them and therefore probably won't be). And assuming the tank isn't terrible, you can usually assume the DPS that are anywhere close to being in danger of pulling aggro are probably the good ones.

So yeah, as a rough gauge, I do usually find the enmity bars sufficient. If someone is really not performing up to par, the bar usually shows it right away.