Not sure which particular parts are confusing, so I’m going to guess and rephrase like this:

People are obviously different, it’s obvious that a certain process can’t fit all sizes, so if there’s a kind of “attitude” with which that process fails, then the problem can be both with the process and with the attitude.

And in my personal experience there are processes which work just fine with that attitude.

Processes are built for human needs. Not humans are built for processes.

So the problem is with the process, which includes the instructor who seems to think that it’s not.