Its because each side is going to explain their point of view in an attempt to convince the other.
Which isn't possible.
...
No.
Human nature has biases, but human nature will not prevent any attempt at convincing the other.
It can easily be a matter of pushing the right buttons (I for example, have already explicitly explained my buttons, as has RDK, hint people, that's the first sign that somebody's being logical, they're exploring the option that they're wrong).
Furthermore, it influences the readers, so it's not just about the debators themselves.
In that case, you wouldn't avoid a surgical ban just because you think it's scrubby. Why would we ban a whole character to fix one tactic? The problem with metaknight is he has too many tactics to surgically ban them all. Not to mention, surgical bans on planking, scrooging, and stalling are quite difficult to manage, due to the subjective, interpretive nature of the tactic. Deathgrabs are clear cut.
Because surgical bans tend to cause more problems then they fix due to the fact that their overall influence on MUs is unpredictable, generally they're a last ditch resort when your only other option is to ban a character because a tactic is so overpowering.
There's also the fact that surgical bans are far less likely to be discrete and enforceable, and bans that aren't discrete and enforceable are pretty useless (see "stalling ban", also known as "m2k gets to stall").
Honestly, that's the statuatory grounds which MK might be banworthy on, evidence is piling up that maybe it's impossible to ban planking in a discrete enforcable way that doesn't basically destroy the rest of the metagame, so banning the best example might be the only option if it actually is overcentralizing, because the other plankers aren't as good at it in my experience.