I would add the costs behind providing that slip of paper are not insignificant.
It requires having people with expert level knowledge of the field assess your work and your knowledge over a broad range of courses.
So universities in the US are ridiculously over priced, but the value they provide is still > 0.
Being part of an exclusive club and having a built-in reputation opens many more doors and makes getting some jobs a lot easier. So then you have to calculate the value of that potential. Department of Education estimated the earning potential for Ivy Leagues to be on average 40k more a year, up to 130k more a year.
If we're comparing a college then with no reputation vs taking only online classes, I wonder if there is much if any appreciable difference per year. Maybe at that point the value of the college education is mostly in the knowledge and skills you gain and the paper itself has negligible worth. So then make sure you're only paying a negligible amount to get that paper.
And then if you want a more formalized course structure, you have online courses like KhanAcademy.
And then if you want to personalize your learning, you can find individuals who are great at teaching that constantly are producing online content. e.g. Grant Sanderson's channel 3blue1brown, popular even amongst professionals, because it re-teaches concepts in a much more powerful and intuitive manner.
I think the internet is already set up exactly the way that you are imagining. The only difference is that you won't get a reputable slip of paper.