I believe GTO is a misnomer. Originally, it was referred to simply as "Game Theory" and then somewhere along the line it accrued the "Optimal", which I think is bullshit. A more accurate name would be GTE or Game Theory Equilibrium. Because that is what game theory is, right? It is the equilibrium where if two perfectly balanced players played each other, GTO is what their strategy would look like to make sure that they are totally unexploitable. Over a big enough sample size, both players would eventually end up totally even (of course, in reality this won't actually happen because variance is a bitch).
So from a perfectly balanced point of view, yes GTO is perfect. But, the thing is, NO ONE is playing perfectly balanced, GTO strategies, even the elite, top level high rollers.
When your opponent deviates from GTO, you should adapt to exploit those deviations. This is easier said than done at the top level, because everyone is aiming to play GTO, so it is difficult to spot the minor deviations, but at the low and micro stakes, a lot of players have not even heard of GTO, let alone know what it looks like or how to implement it, so in this case, while playing GTO will be profitable, exploiting your opponents many, many mistakes, will be far more profitable.
The thing is, before you figure out how you're supposed to deviate from GTO, you need to know what the equilibrium play is in the first place.