I'm not promoting mob mentality at all; The game is already flooded with mob mentality. I'm simply pointing that the support Nunu's ban was because he pissed off enough of the majority of players that would prefer to conform to the point that the system flagged him for communication issues and the evidence was deemed appropriate.
And you have that backwards. The meta and conventional picks are what is proven to work. If the burden of evidence lies in the accuser, then it is the meta breaker that is accusing the playerbase of ignoring a viable pick/strategy, and it is thus the meta breaker's burden to prove AND PERSUADE his teammates that he's right. He obviously chose to simply ignore the necessity of persuasion.
Also, being a one-trick does not necessarily confirm competitive viability.
For example, you can be a Masters tier one-trick support
player. Everyone generally agrees that he's heavily sub-par and detrimental compared to the plethora of other supports that could be made. He's even see as a troll pick in certain instances, and rarely sees play, even in top lane.
BUT, you think you found a viable strategy as a support that only he can fulfill, a niche that has a necessary demand or provides a necessary advantage. In some cases, it might even be better than conventional support picks!
Now just convince your team in Ranked that support Teemo is both appropriate and competitively viable in the solo/flex environment.
9 times out of 10, you won't be able to, because Teemo's role as X champion that does Y thing is fairly solidified, and the strategy you propose does not necessarily correlate with the demands your team is making of you as a support.
Do you pick Teemo support and ignore your team, piss them off, and likely get reported? Or do you pick a conventional support, not piss them off, and not get reported?
Or, to put this in a different perspective, imagine you queued up for ranked in bot lane and your support wants to play roaming
support. He says he has a 56% winrate with it, and this is your promos. Do you just automatically trust the guy with a seemingly ridiculous pick, or do you tell him to play a conventional support?
It's very easy to be indignant about meta-breakers getting banned because these aren't your games that are being played. If your team lets the guy meta-break because he has an evidenced 55% winrate, and he doesn't perform well, then what then? Does the strategy not actually work? Did he just have a bad game? Is it situational? Is it your fault for letting him make a shitty pick?
This is the problem with trying to break the meta, especially in Ranked. The variables in which an off-meta pick work are not generally solid, and more often than not, off-meta picks can be a liability if not handled extremely well. Changing the meta or breaking it desires hard data about in-game performances or true fundamental knowledge and expertise, not winrates. Anybody with enough work can get a 50% winrate on any champion in a variety of given roles, but that doesn't automatically make them viable off-meta picks worthy of competitive Ranked play.
In an ideal world where the meta means little to the playerbase, "playing what you want as long as it works" is fine. But that is simply not true. The playerbase cares very much about the meta, and unless you're some pro player, you're very unlikely to affect it as an individual.