Do you realize that when seen from the outside there's literally no difference between what I'm doing and me being a "bar raiser" or "preventing false positives"? I'm simply using the system against itself within its own rules.
When someone comes in and is able to solve the 2 hardest problems I have cold there's no way I can reject this candidate in a debrief. There's people out there who are able to do this, either through practice or raw intelligence, it's just that they're very rare. If I said I'm filtering for top talent nobody would bat an eye. If you think I'm being unfair you can simply become more skilled at these problems so that I have absolutely no reason to say no, or to not interview in these places (the better approach).