Poker is easy to learn and hard to master. You can advise novices to always raise their starting hands, limit the amount of hands they play, play agressivly and you can improve their game tremendously.

The better you get, the more effort you will need in order to optimize your game. It is the same with basically anything skill based. The learning curve flatens after a while, people´s skill grow slower or stagnate completly. Even if you maximize your own potential, most depends on how good or bad your opponents are.
In times of GTO, we assume there is an optimal strategy, so you can describe your skill as
skill = GTO - your deviation from GTO.

Your profit = villainsmistakes - your mistakes. If villain plays close to perfect , you would have to play even closer to perfect to win. You cannot play better than optimal or perfect.

Even if you play perfect, the margin of your winnings depends on your opponents lack of perfection.

All GTO-approaches , solvers and deeper analyisis tools aim to squeeze out a comparativly small winrate.
All of this takes away a lot of exitement, uncertainty and mystery of poker which are the main factors recreational players decide to gamble.
We are heading to a point where we will still have a small circle of elitist highstakes players and still some lowstakes big losers you just give poker a shot or two, but we are going to lose the poker middleclass.