Isn't "a lot of problems" somewhat of an exaggeration? I don't like DRM conceptually any more than I imagine most people do, but hasn't most people's ire with it been reddit-level sleuthing / whinging?

I have seen evidence that heavy DRM (Denuvo I think, specifically) caused increased loading times.

Apart from that, every time someone tries to prove there is any other difference with any measure of scientific rigour they find no statistically differences.