While it's easy to be cynical and see this as everything getting worse somehow, monetizing a simple idea or premise is tough -- I mean, loads of people just put that stuff out there in comments on social media, blog posts, etc, and move on -- so people fluff it up with endless volumes of filler to justify charging a price for it.
Self-help as a domain is absolutely stuffed with this sort of behaviour, where 300 pages just repeat and spin variations on an extremely simple premise, again and again. The reader tags along, sure there's going to be a twist or next level, but in reality it's just trying to justify this being sold as a "book", when at most it could be a single blog entry.
And yes, every single one of Tim Ferriss' books follows this principal. Entire books can be condensed into one page summaries and absolutely nothing will be lost. Nothing. In many cases one paragraph. Sometimes a single sentence.
This problem afflicts all media. There's a "Glucose Goddess" woman who has made an endless series of videos after she had a book do numbers about reducing glucose spikes. She's spinning four bullet points into endless content and it's just a perfect example. Nothing new or revelatory is being shared, but someone made a whole grifting career on this, all to pitch overpriced vitamins and protein powders.
It's actually interesting that someone mentioned YouTube replacing documentaries because people don't have time for that, so to speak, but YouTube is an absolute scourge of time wasting bullshit. I remember years ago one Apple-sphere guy posting a 10 minute video to answer the question "Should you get 8GB or 16GB in your Macbook". Ten minutes of yapping -- apparently ten minutes was the baseline for getting some monetization metric -- and the answer was an unqualified, worthless "get 16GB", because feels or something.
YouTube recently added an "Ask" AI button, and it includes generating extremely good summaries of videos. So many videos propose some clickbait headline with a clickbait graphic proposing some novel revelation, and in the first few seconds I've seen the summary, see that they have added absolutely nothing new or of value, and click back.
Will these people also post complaints about the drop in viewership about worthless, time inconsiderate content dragging not hitting like it once did? Probably. "Back in my day you could make a career by posting shocked-face thumbnail, a Betteridge's law of headlines question that you promise to answer, and then meander for twenty minutes. Kids these days just don't have the attention span anymore!"