> Have you worked for a FAANG?
I was at Google for 5.5 years and was the beneficiary of an engineer-retention project for a year of that. I'm now working on a startup.
Think of it from the company's perspective: they have an engineer who has already been "paid off" in the sense of having generated more revenue for the company than they are likely to get in salary during a lifetime, and is likely independently wealthy through stock options. That engineer comes to them and says "I'm unhappy here and thinking of leaving so I can work on personal projects." The company does not want to see them on the open market, where they can potentially compete with Google or work for a competitor. So their manager asks them "Well, what is it you really want to work on? Maybe we can make it happen here and you don't have to leave all the perks of Google behind." The engineer says "I've always wanted to do OS development, and there's a bunch of neat research developments like capabilities that haven't yet been incorporated in a production OS." The manager says, "Hmm, I know of some guys over in this other department that have similar ideas. Why don't you connect with them and see if your interests align?"
Google wins because it keeps these talented engineers off the market, and if the project succeeds they can win in a really big way. The employee wins because they don't have to deal with all the risk and bullshit of being unemployed or starting their own thing. Competitors lose but screw them. Consumers probably lose, but it's not a sure thing because if their project succeeds, consumers can win in a big way, so Google doesn't get into antitrust or anticompetitive trouble for it.
This is not unlimited, BTW. The unofficial rule-of-thumb when I was at Google is that "you get one freebie" - if you were instrumental to the success of a project that made Google much more than you're ever likely to make in salary, you get one chance at a self-directed project. If that fails, you either go back to being an ordinary rank-and-file engineer and have to prove yourself, or you get marginalized and usually leave. Public examples of such projects include Google Scholar (Anurag basically ran the crawl single-handedly for many years, and so he gets to indulge his passion project because Google wouldn't exist without him), Golang (Ken Thompson is Ken Thompson and Rob Pike basically built the log handling infrastructure for Google), Google Wave (the Rasmussen brothers basically founded Google Maps), Hello.com (Orkut Buyokokkten's passion project, eventually spun out), and Andy Rubin's robot collection.