You're missing a category because you're focused on the benefits from the students' perspective. Look at it from an employer's perspective:

You have a 100 job applications for one open position. Most of the kids went to mediocre to good colleges. Two or three of the kids went to Harvard/Stanford/other selective college. Who do you offer an interview to?

Keep in mind, you're busy running a business. You don't have time to thoroughly analyze each application. You figure, if they're good enough for Harvard/Stanford/other selective college, they're good enough for me. So you start by interviewing the Harvard kids.

This isn't irrational. Harvard/Stanford/etc. spend a ton of money screening hundreds of thousands of the nations' brightest kids. If you make it into one of those schools, there's a very, very good chance you're at least competent. Elite schools (as defined by things like USNWR) will always serve this function, so kids who want to follow this traditional path to success will always flock to them, or to anything that manages to offer the same signaling/screening effect.

Sure this is a good point. You're referring to the the brand and stamp of approval a degree represents.

I think that's really an extension of the 'skill verification' bullet point. One can easily imagine a program run by a trusted institution whereby a person pays a fee and they are evaluated over the course of a week or so. If they pass, they are given a stamp of approval, if not they either try to improve their skills or go to a lower-prestige institution and repeat the process.

Sort of, but it's more than just a degree and/or verification of skills. As you suggest, there are a lot of ways to test whether someone has some of the skills needed to succeed. If you're looking to hire a java programmer, you could either build or find a short test that would reasonably determine how skilled someone is in java.

Harvard offers much more. They already spent thousands of man hours combing through tens of thousands of applications from very smart kids all over the country. Even if everyone they accepted graduated (i.e. regardless of who gets a degree), they've already performed a talent search you could never hope to replicate.

The importance of college won't change until hiring practices do. Most employers don't actually test most of their candidates on their skills. Until they do they need a way to distinguish their candidates. Hiring from Harvard is a good way to do it since you can outsource your requirements to the Harvard acceptance department.

CS and engineering jobs must exist in a different universe than the rest of the working world. I have yet to go through an interview process that did not require a verbal/written series of technical questions being answered.

It is not much of an exaggeration to say that they do. In many (most?) other professional fields decisions are made based solely on interviews, including finance, accounting, sales, middle management, etc.

Well at least in ECE/CS fields, we have the luxury of more liberal hiring practices in which personal projects on resumes and githubs can matter just as much as what school you went to if not more.

It's much harder to measure the quality of candidate in other fields without the context of what school they went to and how well they did there. (Unless, of course, you have time for a full-on interview. I think parent is referring to the screening process though)