UPD: I have provided negative feedback to my recruiter and they still reaching out to me. Really doubt companies ever act on any of candidate feedbacks since candidates are not employee (I know my previous company didn't, asking for feedback was just a "wanna look good in your eyes" question).
And what happens later when the market is not so hot? I was around for both the dot com bust and 2008 recession. The current hot market should not be taken for granted; it isn't going to last forever.
I'm not looking for a leetcoder. But I've had to reject candidates who otherwise seemed really strong, but then it turns out that they completely struggled with every aspect of a simple python question.
The difference is that a candidate with a good attitude and growth potential is usually worth hiring even if they're not a fit for the role they applied for, and so the hiring manager will get creative trying to make something work.
Perhaps some of the well known tech companies don't put the same level of care into their interview pipelines, and then folk become jaded and irrational? Does anyone remember that Office episode where Ray Romano interviews for the manager position and talks about how all his old coworkers are jerks while eating a sandwich out of his briefcase?
In my experience, it turns out to be some dark corner of the language, or a keyword that's not in common use today. Examples are: 'void' in JavaScript and 'boxing' in C#
Same result as you: The recruiters stopped bothering me.