No, not everyone does that, and it is not objectively a good thing. It can be a good thing, but depending on your game design it can also be a very bad thing.
The top level is always the vast minority. If most people think something is OP it probably should be nerfed, even if the players at the highest level dont think so.
Because if the majority of players struggle heavily against something, then it takes away the fun from the game for the majority of players. If something is easy to win with, but useless if countered properly it might not be objectively op, but still destroy the game, if the way you counter the strat/civ is significantly more difficult than playing that strat/civ.
Adding to that: An underpowered civ/strat does not hurt people dramatically. An overpowered one does. Even if it is just over powered at a lower level, it will still hurt the majority of players.