Facebook's shadowban mechanism is more elaborate than that. They will still show the post to people they think you are closest to, while hiding it from the general newsfeed where most things show.

The Facebook newsfeed is quite similar to TV, because you can only change channels, but have very little control over what is displayed.

Every post gets scanned. They detect things like blacklisted links in real-time.

Algorithms. It will find you eventually.