Well... for me broken and overcentralized are kinda separate.You seem to be reasonable enough. Once people explain something to you and it is clear your position is not as good as theirs you admit defeat. It's fine if you weren't being serious and you were just joking with him, however I'm confused as to how you can be so black and white about his brokenness (if you are serious).
If you say that once Meta knight becomes 50.1% of the brawl population you consider him worthy for a ban, why is it ridiculous for someone else to draw the line at 40%? Or whatever percent they are under the impression it is right now? Does the majority really have some magical quality to it, when the thing at stake is the diversity of brawl? You can't state as a fact that he is not broken just because someone else draws a line at a different point than you do. That's opinion sir.
When it reaches 50.1%, then it would be overcentralized, but I see how 40% would work as well.
However, Meta-Knight isn't broken. Since it has been brought up multiple times, I pose Akuma. Akuma was broken, as it wasn't possible to defeat him with any other character but himself.
Meta-Knight is beatable. He actually has near-even matchups, which many people believe as even. If he doesn't break the game to the point where it's impossible to win against him, then he is not broken.
Here, let's use urban dictionary for a second:
Look at the bolded area, for this is what applies. Meta-Knight does NOT meet this criteria. Akuma did, however MK does not. Therefore MK is NOT broken.1. broken
1. (General) Something/Someone that is so good in a particular context that it eclipses saecond place.
2. (Games) A game object or facility that is too good to exist. It is so powerful that it is unbalancing and hence breaks the game. Every winning player has to use this to be competitive.
Entymology: The power cards from Magic The Gathering (Black Lotus, Time Walk, Ancestral Recall, all Moxen, etc) were so powerful and unbalancing that they were eventually banned from tournament play because they BROKE the game.