I like venturehacks (actually a lot) but blogs in general have just as much "de-valued themselves into the garbage can." At least when you are in an MBA program you receive information from different disciplines (HR, Strategy, Operations, etc, etc.) With blogs you first have to get past the fact that the top 20 are just one big echo-chamber.
But the MBA programs have already de-valued themselves into the garbage can. The burden is on MBA programs to prove that they are valuable as these blogs, not the other way around.