That second point seems to imply that any number of people (A B C D E...) can have a specific PS4 (A) as their primary simultaneously, and any two within that primary (A) pool can play a game (that’s on A’s account) simultaneously. I’m guessing that’s not true, that a console can only be primary for one person at a time, and the phrase “share your games with any number of people” glosses over the fact that you’d have to do the primary console tango each time another person wants to play one of your games.
But running two instances of a single copy of a game is pretty cool. It can essentially halve the cost of a game.