You're assuming that that awareness of how to solve a problem and immediate hands-on-keyboard test for materially different success rates while actually employed. My experience is that by the time you've gotten the job, most of the crammed-in Leetcode specifics have leaked back out and you're in the same place as somebody who knows the thing from school or from using it in prior projects, but didn't have it in their fingertips during the interview--you're looking it up again, because you know what you need but don't have the details top-of-mind.

The insistence on being able to spew out code-first answers to contrived problems during an interview situation is silly gatekeeping, but it makes the people who pass feel good, and that's why it persists.