The point is that most of the time you're not actually hiring for specific niche skills that the rest of the team don't have. You just need more capacity to do what the team is already doing. In those cases if your tech test is some Leetcode algorithms question that the team can't pass themselves then asking that of a new hire is silly. You'll be ruling out candidates who could do the job well, just because they can't pass a test you don't need them to pass.

All I suggested is using the team's existing skillset as the measure to hire new people for the team, rather than some sort of arbitrary test that doesn't reflect the work they do.