The problem with this advice is that solvers are one of the best ways to understand how to "exploit the shit out of your opponents".
Piosolver has several features that lets you emulate how your opponent plays, such as "node locking", that "lock" the game tree node to the strategy you suspect your opponent plays, and shows you how to maximally exploit it.
Otherwise, what is your exploitation based on? Certainly some people have great instincts for the game, but it's just untrue that solvers can't help you exploit weaker players. For example, if you're on a given board and a given river and an opponent makes a big bet, if your opponent bluffs too much you should call, if they don't bluff enough you should fold. But the solver teaches you how often they should be bluffing and thus what "too much" or "not enough" even means.
This is why I prefer the term "theory-based" to GTO, since the point of studying GTO is not to play GTO but to develop a better understanding of the underlying mechanics of the game.