Yep, that's my experience too. Most slider sets end up making the game easier. Tried the OS set and it was the same, and when CM is already too easy at default, it's just not a viable option for me sadly.
If you do use sliders, I'd suggest playing on Ultimate and going from there - playing on Ultimate you get the most intelligent version of the AI, which IMO if you're going to adjust sliders you might as well start from the place where you're getting the best version of the AI. The only problem with that is you do get more of the first touch passing and shooting, which can be frustrating.