That's crazy. When I joined FB a few years ago the total time was under a month.
The reading list thing makes sense for some people who have never done a FAANG-like interview before. I remember moving from London to the USA early in my career and I had no idea how the process worked and so I got my first phone screeen with Amazon, thinking I'd explain a bit about my background and we'd have a bit of a chat and instead I got "Okay. Give me code to perform an in-order traversal of a binary tree." which was NOT something I was remotely prepared to do at the time :)
If you know the format and basic types of questions (and have access to leetcode etc.) it's not too bad, but a lot of these resources weren't around 15 years ago, especially to people from another country with no context.
A second Amazon interview aside: in an in-person interview I did, things had been going very well and I was on my fifth interview of the day. Again, I was recently from London and hadn't fully understood that words mean different things in the USA than they do in the UK. I was asked to design a GPS system. This seems simple enough if you know that "GPS" in the USA is the same thing as a "SatNav" or "Satellite Navigation" system in the UK and that the goal would be to build a system that could compute an efficient route between two points.
The problem was that I assumed the person wanted, well, a GPS system. i.e. he wanted a design for a set of satellites in geosynchronous orbit that would, using very precise timing, allow a person almost anywhere on earth to get a latitude and longitude like "12.345, -2.345" and so we spent almost the whole of the conversation talking about two different things and even when I was given the hint that maybe I could use some kind of graph algorithm, I had no idea how to use Dijkstra's to solve clock drift on a satellite :)
For some I guess it'll be worth it, but this insistence on that approach then means they're causing the candidates with enough experience to get competitive offers elsewhere to self-select away.
There's a ton of people on the internet who claim that they just haven't done enough leetcode to get into FAANG but they're sure it's The Way, and anyone who is in FAANG cannot possibly dissuade them from this belief. I imagine they're reading the interview prep books too and still not getting in.
I'm senior enough that I don't need to deal with that bullshit to get a well paying job, so in not trying to sell me on why I should want to work for them but instead giving me junior level "homework" they made me mentally raise the bar for how much money it'd take to make it worthwhile quite substantially.
Maybe they don't want people like me, and that's fine if that's an intentional choice on their behalf and not an effect of failing to realise that it's pushing away the most experienced candidates who have other options first.
Add to the fact that I was hesitant to even consider Facebook to start with and it was easy to pass on it.