Well, i have worked at Amazon, for less than a year; My rather limited impression was, that this is a very dysfunctional organization. Now if this impression is correct, then the leetcode appoach has some merrit; the leetcode approach would select for people, who stick to the technical part in the narrow sense of the word, and who would not question the state of things too much.
Working like that, at least at Google, will only suffice up to about L4. If you're good at leetcode, you might be hired at L4 directly, but if you're a normal person then it means you have one promotion before you need to learn completely different skills to advance.
I do nothing that looks anything like leetcode whatsoever.
But I guess, that this is all speculation..