That's not true, but it is a commonly shared myth. I've taken and passed C2 with the highest mark in every category (I moved here when I was a young teen, wanted to know if I would pass it after hearing years of people saying things like you're saying).
Most Germans would easily pass C2, although I think they'd have to be well-read/possibly university educated to get high scores (mostly need to be able to read quickly, give a semi-structured presentation and write a persuasive essay).
For what it's worth, I could run linguistic laps around all the other test takers there that day, and I assume at least some of them passed.