At some point there is more to your contribution than your code
It seems to me that the issue here is not only (or even mainly) about how developers are treated on the kernel developer community. It is about maintainers and reviewers being told how to treat others. Many people find it easy to tolerate watching people yell "You're an arsehole!" at each other. There are fewer, but still a significant number, who can cope with being told "You're an arsehole!" from time to time. It's a lot harder not to take it personally when you're told "Be an arsehole or fuck off!". No matter what we feel about the relationship between our code and our selves, how we interact with other people is very intrinsically us.
The approach which many senior or long serving maintainers have found works for them ranges from abrupt through aggressive to ad hominem. The attitude seems to have gone from "It works for us, it will also work for you." to "If it's not working for you, it's because you aren't sufficiently like us.". So when claims are made (including by commentards above) that the USB 3.0 project wasn't producing as good a result as it could the criticism very quickly falls very personally on the maintainer.