The issue for me is that even if you have strong computer science fundamentals and lots of experience most of the time you won't be able to come up with an advanced optimized algorithm (that took years of research) on the spot, which is what is often required in these kind of interviews. Even if you manage the average kid that grinded leetcode for years will appear a better candidate than you, maybe he really is, but that's unlikely on the day-to-day job. In the end it's just about who grinds more, obviously if somebody is really weak on the basics it shows immediately without having to go through the hops, fizzbuzz is enough.