A signal, I can agree with that. But isn't that only because someone is unable to signal that (s)he can be a valuable asset in other ways? The type of person to only rely on their degree is probably a person that isn't creative enough to find more effective ways to market themself.
I think education is great and learning new things is massively important in life. I just personally don't believe in the degree fetish that a lot of people have. Just look at the quality of the average graduate in a lot of universities and/or colleges in the US and Europe.
To me, at best, a degree is an inefficient way to differentiate yourself from a group of similar people with similar skills. Maybe not a bad thing if you're at the start of your career. But at worst, it has zero additional value.
I don't see that working for a lot of other people I know.
I think the US is approaching numbers where you might really be better of without a degree in a increasing number of fields.
It's the reality of the situation, and until there's a significant change in attitude, not having "a" degree is going to hurt your career prospects unless you're a wildly successful entrepreneur or have great connections/independently wealthy.
Just provide free community college to everyone for a 10th the price and call it a day.
If anything this argument would suggest that you should have a private system of education and the government should spend all this money on research grants for things that are interesting, and/or useful.
There is a lot of study on the idea that the main value of education is not what you actually learn but much more signal that you are dedicated, motivated and have the ability to learn.
There is a huge argument going on right now about how much of the value is signal vs actual knowledge you need for the job. There is a lot of evidence that suggest that signal is a huge part of the value.
Network does not really apply as a expiation because the effect appears even when transition to a place that you have no relationship with it.
If you are interested consider listening to this: https://www.youtube.com/watch?v=bpk_u_VmPD4
(Be aware, this is a strong version of the argument, deliberately picked to break with the tradition view that many people have)