Every walled garden has an innate desire to prevent users from leaving…that's the whole point, after all: collect eyeballs so they can be monetized.
Of course, the actual monetization process often necessarily involves allowing those eyeballs to trickle out of the garden, so a better metaphor might be a reservoir with a hydroelectric dam.
Every social network seems to go through a rite of passage that involves intentionally breaking any non-monetized link out of the garden. Most seem to eventually relent, but now it's TikTok's turn.
Following on from the link right above…what if your hydroelectric dam had a magical way to put the water right back into the same reservoir?
That's how we get to content fortresses.
The first-order rationale for this upcoming change is obviously 'tracking': if you can't reliably get out-of-garden measurement anymore because Apple tells you it's not allowed, the only solution is to bring it all inside the garden, right?.
But doing it this way has second-order benefits for the walled garden model too, because now the eyeballs can check out any time they like, but they can never leave. Privacy changes just provide useful cover, because brands would never have accepted it otherwise.