You miss the obvious point: The Williams sisters were turning pro; they didn't go to college. College student-athletics should be different. Granted, it isn't much anymore--but it should be.
Somehow, this notion settled in that college athletes were being exploited by their schools, which IMO is mostly nonsense. Most revenue-sport student athletes are getting full scholarships that, over 4 years, are worth well more than $100,000--probably closer to $150K or more when you consider housing and food. Do you know how many college students who are not student-athletes would like $100K to pay for their college education? All of them. They not only have to pay to go to college, most have to borrow as well, getting saddled with student debt. So all of these hand-wringing about poor football and basketball players is the usual jive talk. We've got colleges now who are paying student-athletes to get decent or good grades. More nonsense. It's like, well, we can't expect these players to be responsible, so we have to bribe them to stay eligible. Most take very easy majors in the first place, and so getting good grade in a sports-management or general studies (whatever that is) major shouldn't be that difficult in the first place.
Beyond this, NIL is just a license to bribe high-school prospects. Some Alabama coach can tell a 5 star prospect that he's got a bizman lined up to do a NIL with him. Maybe the booster/bizman gives the kid, say, $10K or $20K as part of some supposed NIL deal. Maybe the bizman has 100 T-shirts printed to make the deal look kosher--and that's the end of it. Very few student athletes are going to get an NIL deal in the first place, and of those who do, only a handful (at best) even have the possibility of making decent money. You might have a star left-guard on your football team--but fans are not going to go out and buy Star Left Guard T-shirts. In sum, this idea that student-athletes who are getting an expensive four-year college education for free--along with food, housing, tutoring, crisis management, etc, etc. AND the training/coaching that could them in a position to earn a pro contract--are being mistreated is total BS. They've got it better than all other college students in the country! And paying them to get decent/good grades? Pathetic. And, as mentioned, you've just, with NIL, pretty much give boosters a license to bribe high-school prospects. It used to be done in the dark and was illegal; now, it can all be wide open--and there's NOBODY to monitor any of it.
As for the portal, the transfer thing has spun out of control--but as others have noted, it's easy for coaches at top programs to cast aspersions on the portal, because they recruit very well to begin with. It is clearly more help to programs, like ours, which are not as strong--but even so how much help are most transfers. In some cases they can be a lot of help--look at our QB--but in a lot of cases you're just getting players who were not getting PT at other schools, and there's usually a reason for that. I don't think there is even a limit on the number of times a student-athlete can transfer, is there? If there isn't, there should be--limit of one, or maybe two, I can't decide. It's also worth noting that a LOT of student-athletes do NOT improve their situation by transferring. Some do, but a lot don't. And most transfers can't pick the next school they want to play more. A few can, but a coach has got to want you. You may find a school where you play more--but it may be a lesser, lousy program.