Demonstrably yes. The entire J-school educated mainstream media has had the opportunity to do the story that Arrington has done, and yet they have failed. He has done the work that they have not, and done it well. By those credentials, among his other work, he has proven his suitability to cover technology.
Blogs are not yet a replacement for all of mainstream media, but that is to be expected. Blogs are young, and profitable blogs younger yet (5-10 years at best), whereas the mainstream media is still a multibillion dollar centuries old institution. The fact that blogs are any competition whatsoever to the mainstream media is a shocking condemnation of the current state of mainstream journalism.