C programmers tend to reach for the preprocessor in cases where other tools would have been more appropriate. In particular, #ifdef. If you haven't experienced this then maybe you've worked with people that have uncommonly good taste.

I agree there's nothing particularly terrible about the preprocessor as such, if used tastefully. Especially if you compare it to other macro engines like maybe TeX, CPP strikes me as quite simple and clean.

Even newer languages like Haskell choose to adopt it after all.