Unless these skills that are interviewed for are directly translateable to the job, it seems like this "prep work" filters out busy candidates who are already working and have families, kids, lives. Actually maybe that is the intention, QED

While this may not be inviting to you, I think there is a flip side to the "wide-net" that big companies cast on LinkedIn and such. Instead of just hiring from a pool of "well-established" candidates, they give a chance to a wide variety of people from different backgrounds - as long as they can pass the interviews.

This may not sound like much to anyone who is established in the industry or happened to be in the right places for a good career head-start, but for people coming from non-traditional backgrounds, industries and especially places where there's no tech - being able to study-up and land a job at some of the most well known names in the industry can be life-changing. I think this is a very under-appreciated side effect of the "recruiter spam" from FAANG that everyone seems to dislike if they can afford to.