We don't do this, actually. Our take-home code challenge is fairly straightforward (I suspect anyone with 2-3 years of real-world experience could complete it in a few hours). I do spend about 45-60 minutes per candidate in a phone screen to talk with them and get a sense of their experience. Our on-sites convert to hires at a pretty high ratio, because I try not to bring people on-site unless I'm pretty sure I'm going to hire them, and while we do a few whiteboarding exercises, my team is trained to ask questions that don't have a single correct solution. This isn't about memorizing trivia questions. It's about critical thinking skills and problem solving in real-time, and that's what we're trying to measure. If I give them a question and they take the entire 30 minutes to get halfway to the answer, that's OK.
But, having interviewed at a number of other companies in Silicon Valley, you aren't wrong. Most companies optimize on the FAANG dimensions and it's not particularly accessible for anyone who hasn't spent months grinding on those challenges. Not a good way to hire, imo.
