I grew up in Germany, went to an okay university first, then a "good" university, became a management consultant for a while, enrolled in a relatively high end business school, went to Cal to do research and finally ended up in the Bay area and went through YC a while ago.
There were very good (by some metric) people everywhere I went. I'm talking about the top of the class when I studied Math in Cologne, the 30 y/o tenured CS professor in Munich, the 22 y/o consultant who earns more than his parents etc.. Those people are often focused on achievement, grades, getting a good job, etc.
Recently, I've met a different kind of people. People that I'd consider great at what they do. The people that you can ask a stupid question and they'll give you a considerate answer, the ones that do things out of an intrinsic motivation. To find out if they want to work with you, they'll sit down with you and talk, or work a problem over. I've had to write resumes all my life and then suddenly, a few years ago I stopped maintaining one and never needed it either.
I think what I'm seeing is that at the very high end in whatever field you're in, people won't care about credentials. But unfortunately, there is a middle ground on the "slightly less high end", where it is very important. Perhaps what you can do is "keep up appearances" until you pass that stage. If there's an easy way to get credentials (i.e. I don't think I benefited a lot from any degree I have, but they were easy to get and I could do other things I liked more at the same time), go for it.
Edit: Sorry if this lacks clarity, I wrote it in a hurry. I'll come back later to edit