They didn't mention the increased availability of student loans, and that's the main culprit.
They did mention it, first in the title. IN fact its kinda the subject of the whole article.
What you have stated is a myth based on the faulty presumption that colleges and universities behave as entities with profit motive. With rare exception, both public and private universities are not-for profit (on a side note, there is growing evidence that the for-profit universities suck)
In fact, it is the other way around. Rising college tuitions make student loans more necessary for students to attend school.
Colleges and universities can increase their prices because people can pay it.
That's not even strictly true. The public universities in my home state cannot increase their tuition without approval from the legislature. The legislature won't approve an increase in tuition simply so the university can pad its coffers, there needs to be a demonstrated need for the increase based on the increase of cost.