Just because you aren't running Facebook doesn't mean they aren't in your device. Many apps and sites contain Facebook libraries for logins, sharing, advertising, and analytics. If they include any of those, you are automatically sending data back to Facebook. With the way things are currently setup, Facebook can easily tie your activity in one app to your activity in another app. And as we have known for years now, Facebook creates "shadow profiles" for users it can't identify and attempts to tie those shadow profiles to real life people through the actions of their friends on Facebook and its other products.

So even if you use no social media whatsoever, Facebook is still compiling data on you. And this change in iOS will greatly limit their ability to do so (or at least increase the work necessary to accomplish it).

Frankly, it has me considering switching to iOS as well after running Android for over a decade.

Apple App Store rules (will?) explicitly ban all kinds of tracking without permission. If you try, your app will quickly follow Fortnite to the abyss of banland.

The tracking permission is an OS level popup with strict rules on when, how and how often to display. The default is opt-out, it's up to the app maker to give users the incentive to allow tracking.