I'm pretty much the opposite of what you think, so if my desire to study for the algorithm interview is your litmus test for that, kinda proves my point.
Not everyone that would be good for Google has a burning desire to work for Google. Google might want to consider that.
What I described on my previous post is a credible explanation that my group of engineer friends came up with on why all the FANG companies pursue those heavy memorization algorithmic interviews.
It is also a safe place to work for the really exceptional engineers. They can talk freely about complex computer science, without getting blank stares or having to dumb it down. Otherwise it gets frustrating fast.
I think the most likely explanation is that "elite" of CS grads usually do competitions like ACM ICPC and olympiads, which are full of problems like those watered-down interview questions. As there is no real authority on what makes a developer good, but there was a measurable outcome of those programming competitions, leading to high status and pride displayed by winners/participants, it was simply taken from there and dumbed down to fit into interviews. Some top colleges even have special prep courses for those competitions and comparing to them FANG interviews are super trivial.
