There is nothing inherently wrong with your whole team gaining exp for battles, that's just how regular RPGs have been doing it for a long while, having it off isn't adding difficulty to the games, it's just adding tedium of having to individually grind for each pokemon in a team. But, the way pokemon handles it is wrong, the whole EVs shit like mentioned before comes to mind, not to mention things like friendship/affection
>>58115030>EVs were done best in gen VI with Super TrainingI'd argue that gen VII also did it well, albeit in a different way, you could just grow the EV berries without having to worry about taking care of them thanks to pokepelago, and one of the islands let you just leave your pokemon for training. Sure, it took time, but you could reduce a considerable chunk of it with the beans. Super Training did it best due to how much of a time saver it was, but if you could only ever play a few hours per day due to work or other factors gen VII's was more convenient due to wait times becoming a non-issue