I've tried to type out several pithy comments, but the bottom line (to me) is that Facebook just doesn't respect its users or care about their needs.
Can you imagine if brick-and-mortar businesses tried to do this? You go out for a Big Mac, but it's not on the menu anymore because Taco Bell had a few really good quarters, so McDonald's decided to pivot to tacos. Maybe you can still order the Big Mac if you know to ask for it, but most people won't, and they'll leave disappointed instead of getting what they wanted.
Edit: To clarify, this example is contrived and the details are not the point. The point is that Facebook offered something to their users, spent years and billions of dollars making sure that as many people as possible got it from Facebook, and then decided to just yank the rug out from under all those people to chase the fairy tale of endless growth.