What about the rest of us, who don't have "star-power" or anywhere near the kind of platform that Zach has? If you're just Joe (or Jane)-average programmer, yes, startup interviewing is fucked. Doubly so if you don't live in SF or SV.
A lot of these interview questions are 'crap' but designed to be solvable in 20-30 minutes and not require hours of domain specific knowledge. In other words, it's something _anyone_ with _any_ degree of problem solving skills should be able to solve.
Onsite interviews should consist of working with another engineer to look at a real problem the company is dealing with (or was dealing with in the past) to see how the interviewee approaches the problem and tries to solve it. It's not about reaching a solution per se, but rather how well the candidate works with the team and if her approach is the correct one.
From my time at /r/cscareerquestions, LeetCode is the "hardest" and thus the best for top companies. HackerRank is good but every challenge requires parsing STDIN instead of just giving arguments to a function the user writes. It's very annoying to me and a deal breaker, especially with certain languages.
Eh, he built that platform. Not sure I would call it luck or privilege.