A problem seems to be that smart jerks know that people would prefer to not be around them and therefore spend a lot of time/energy/intelligence making themselves organizationally powerful enough that people have no choice. I think this is sometimes called "playing politics". Prevention seems to require actors who are both politically savvy and kind, and that doesn't seem to be easy to find.
problematic employees need to be fired as soon as possible or they ruin everything they touch
This does not work in practice. Often the "problematic employee" has a management function and is the "golden boy" of the big boss. I have seen it two times, were an idiot "golden boy" nearly tanked a company. Everybody knows who the problem is. Only the big boss does not.
That doesn't negate the fact that firing them is the right solution. Just that the right solution is hard.
They still need to be fired, even with the boss protecting them.
And in the real world, how would you convince the top decision makers to do such, without causing more damage than what it prevents?
I don't know. But from the employee perspective I can tell you: It is never too early to fire your job!