I say memorization because they don't allow you to look anything up. I can, for example, look at a problem and remember vaguely that there's an algorithm and/or data structure that's ideal for solving it and some of the high level concepts/keywords I would need to find it. I also know the right google foo to find it again, see if it's still current best practice, find a decent implementation of it, where good documentation is, and so on.

I can't always bang it out on a whiteboard from memory though. If I could, I don't think that would somehow make me a better developer. It might make be a better T/A in an academic environment, but that's not typically what these kind of interviews are hiring for.

Which basically limits to newly graduates or those lucky to work in domains where dealing with leetcode style programming is daily stuff.

Yeah thats fair , definitely agree that its more useful when interviewing new grads