Yes and No.
Any of the big names that are switching schools have been "tampered" with via family/agents, etc. and almost assuredly know where they are going once they officially enter the portal. At this point, the industry norm (for lack of a better word) is that they still enter the portal - but the give away that they already know where they are going is the "do not contact" designation and they are just playing the game of making it look official. The act of entering the portal, even if it's just for show, is all set up by the school that you are leaving - kids can't actually enter the portal. They just have access to it once an official from the school enters them. That was part of my brother's job when he's an associate AD. I am not sure how much longer that charade will even continue. As we just saw with the Wisconsin kid, there really isn't anything preventing a kid from unenrolling and enrolling somewhere else at any point in time.
Where the portal process actually has value, and what will probably become the only use of the portal in the near future, is the kids who want to transfer out but aren't at the talent level of being tampered with. It gives them an opportunity/marketplace to shop around and makes the process easier for them.
I'd be fine if we just did away with the charade of big names entering the portal and saved people the work of having to enter them so that they could focus more on the kids who actually need the portal to find a new home.