I already told you. It makes it harder for older, less educated people who aren’t up on the PC subculture to talk about issues where this language comes up, because they are afraid of saying something ‘wrong’ and being embarrassed/shamed/accused of being a bigot, or even suffering more serious consequences like losing their job. And many times these are important issues which people need to talk about.
Also, it’s annoying in the same way as corporate buzzwords are, and provokes the same resentment. It’s obvious that to some extent the adoption of new PC terms is driven by the same forces as teenage slang - demonstrating in-group affiliation, showing off how clever you are, fashion - but the rest of us are not expected to keep up with and correctly use teenage slang.