My feeling is it has gotten much worse as people have sought degrees solely for the purpose of using them to get jobs in the field, precisely as you suggest would happen to blogs and reading cliff's notes.
However, may I point out that blogging is very different from reading the cliff's notes of a book? A hiring manager can read your blog. If they simply check that you have a blog, well, whoop-de-doo. I have a blog, so that clearly proves nothing.
However, if the hiring manager reads your blog, they can deduce a great deal about what you pretend to think and how you communicate it. So it is a small example of your work, much as posting source code is a small example of your work.
You still haven't told us who Ayn Rand is.
The ability to write blogs is irrelevant here too as what we most likely care about is the ability to program. Hence, the programming test.
Now take the group of programmers who have written less than 30 blog posts about programming. Y% of them are good hires, and 100-Y% are bad hires.
Is X > Y, or X == Y, or X < Y?
That is the issue.
And that is the way degrees are used (when used rationally). The claim with degrees is that X is more than Y, not that most good programmers have degrees or anything else. That may be so. Then someone defended using degrees by saying there is a lack of alternative tests that are sufficiently cheap. That's not true. There are lots of cheap tests, and I have suggested 2 for which I believe X>Y is likely, and which, if studied, might turn out to have a higher X than the degree test.
My point was is that even though it filters out many of the worst programmers it would also filter out all of the really great programmers. I'd rather have my search take longer and cost more to have those great programmers on my team than end up with just good programmers.
If good programmers read Rand or write blogs at a higher rate than bad programmers, then it works, even if it's frequently wrong about individual people.