At most levels, just being very very good at a few characters, even if they're off-meta picks, will do better than someone who picks on-meta and doesn't have a good fundamental skill with the champion.
Now, most players keep a pool of champions they have solid (or at least better) fundamentals so that as the meta shifts they can fall back to others. Additionally there are cross-champ skills like strategic considerations that can carry you.
It's also weird because in MOBAs the updates literally change the balance of the game, so by some definitions this actually changes the fundamentals which causes the meta to have to react. So really most players are chasing relearning the fundamentals (oh geez Zeus is nerfed into uselessness!).
One pretty weird fundamental is to get good at coaxing your teammates to make a reasonable team comp without causing anybody stress
> It's not until you reach a level where everyone around you has a mastery of the fundamentals, that the meta comes into play.
At any given MMR bracket, everyone around you has a similar mastery of the fundamentals so the meta is relevant.
However, put someone with the fundamentals of a 6k+ MMR player into a 3 or even 4k match and they'll demolish everyone else even with a disadvantage relative to the metagame.
The original comment said
> It's not until you reach a level where everyone around you has a mastery of the fundamentals, that the meta comes into play.
and you said
> At any given MMR bracket, everyone around you has a similar mastery of the fundamentals so the meta is relevant.
which refutes the original comment.
> However, put someone with the fundamentals of a 6k+ MMR player into a 3 or even 4k match and they'll demolish everyone else even with a disadvantage relative to the metagame.
I don't think anyone disagrees with this; I think the issue I (and the person you're responding to) have is the idea that you should ignore understanding the meta until you're 6k MMR as you say.
Both are important and you should develop both at the same time if you want to improve.
Zeus is never picked? Great! Don't need to learn that kit. Or perhaps digging into why Zeus isn't picked can help inform why another character is more useful especially in conjunction with others in a team.
A player with no understanding of the meta but good fundamentals can easily be directed by their team and have the same output as a high(mmr, meta) player. However, direction will not always be available and this will result in some losses.
A team full of players with high meta knowledge but low fundamentals will lose the fundamental game too hard and lose most matches. Also experience the "too many chefs in the kitchen" effect.
A team full of players with high fundamentals but poor meta knowledge will perform reasonably well, but be outshined by a more balanced team.
The team that won the largest DOTA championship 2 years in a row was clearly one that on balance had medium fundamentals (at a pro level), and outstanding meta.