I think this is perfectly fine, though. Once you know the system you game it to gain an advantage. If you feel it makes the game too easy for you, you don't have to exploit its weakness. There's nothing wrong with being overpowered with knowledge. You don't start with knowledge.
If you find the game too easy with your resists, you could set down rules for yourself. For example no resists. Or no mgaic/rare/legendary gear, only allow yourself crafted gear. Or no bartering etc.
Finding these "weaknesses" in a system and taking advantage of it, is exactly the same thing as, for instance, finding the most efficient way to level, or finding the most complementary build of skills and talents.
You don't always have to only play with difficulty that's handed to you on a plate; you can create your own difficulty.
