What a load of crap... "why do schools focus on unmarketable skills?" Gee, I don't know? Maybe because we shouldn't be teaching kids that they only exist to learn about a trade so they can be another cog in the machine? Because there are things worth learning beyond just what's valuable to the job market and every person should be given the opportunity to branch out and be diverse in their studies?
Colleges give you all those supplemental classes so that you'll be well-rounded. Sure, you'd graduate faster and spend less money if you only took the classes that were immediately relevant to your career, but math proofs and math in general aren't always practical... it's about training your brain to solve problems, and the more abstract you can think about and approach a problem, the more creative you can get with your solutions.
And it's not even just about skills... college is a whole different ball game than High School in terms of meeting new people. High School is all about cliques and for a lot of people (myself included) was fucking miserable. College allows you to meet a diverse set of new people who may or may not share common interests and for me, at least, allowed me to grow as a person in ways that don't necessarily translate to anything "marketable".
Sure, not everyone is meant to go to college and the mentality that our parents had when we were younger, that "you have to go to college or you'll be flipping burgers for the rest of your life" is toxic, but those of us who do want to pursue a career that requires a higher education shouldn't have to spend the rest of our lives in debt just to do so.