There are a finite number of optimal strategies for any game, and this number is much smaller than the suboptimal strategies. If your opponent is playing with a better strategy, his odds of winning are higher unless you are simply a better player and can offset that with skill. That is the genesis of the meta: a standardized set of strategies that are understood or believed to be the best way to play, and if followed by all parties should let skill be more of the deciding factor. That is to say, whoever wins did not win because of a better build order, or jungling rotation, but because they executed everything better. They aimed better. They made better targeting decisions. They played as a team better, and so on.
All that being said, the meta is certainly not gospel, nor is it always correct (if it was, it wouldn’t evolve). But, players who deviate far from it without good reason and obviously poor results probably will hear about it from some teammates. It is a finicky situation because while one can easily argue “I can play however I want,” one can also counter with “Sure, but when the fun of nine other people rely on you, should you?”
In other words, no one would care at all how anyone played if their play did not directly impact anyone else, and when it does I feel it fair to expect some accountability from others. This does not mean you need to adhere to the meta, it is more along the lines of, “I am going to do my best to help the team win, and I can expect others to do likewise.” When a whole team fulfills that contract, it is usually pretty fun, win or lose.
Of course, there are always going to be toxic players that demand you play one way (their way, naturally), but as long as you are genuinely trying to help win I don’t think anyone has much room to comment on how you play.
