It is true, most of the leetcode problems use the same underlying collection of approaches. If you don't know them (by memorizing them), you probably won't solve the problem. There is some value in knowledge of those approaches (algo and DS stuff), but these toy problems are not a good way to evaluate how someone would use then in a real life situation.

"95% of programming is data structures and algorithms" - it's just not. 95 percent of programming is gluing together libraries, refactoring code and reorganising what you have to solve new business requirements.

Your focus on performance (albeit important) above all else makes me question how much real world experience you have building large scale systems. (Unless you're a systems/embedded developer).

But this is the crux of the issue: using metrics that don't map well to what we're trying to optimize for. Perhaps your trying to optimize for finding great performance focused, low level software devs? If so that's different that my goal.