This is something open source gets right that companies don't -- in open source, there is a credits list. Both in the contributors listing and in the actual publicly accessible history of commits itself (which in turn auto-generates contributor lists e.g. on GitHub).
I'm an example myself, as I started in the industry working on a strategy-genre game, and talking shop about the genre makes me more appealing to studios that serve that.
Google, on the other hand, appears to be exactly opposite [1]. So, it appears that, for somebody who worked on Gmail and pursuing the similar line of work in a company similar to Google, proofs of experience would be of little value.
1. https://www.quora.com/Whats-the-logic-behind-Google-rejectin...
That distinction is where some of the wish for credit comes from I believe.
Instead I have a resume and references which can be checked to determine if what I'm saying is true.
Now being able to do that automatically is great, which means we should just take the whole process on our own hands as software developers and create something that represents us?