Isn't this a Catch-22 though? In order to show that you can contribute PRs to the codebase, you must first get hired to AirBnB. And in order to get hired, you must first show your ability to contribute.
You mention that a way to show ability to contribute is through "professional references and career advancement", but doesn't that also first require that you get into the company first? For the former, you need work to find colleagues who can give meaningful references, and for the latter, you need to enter the job first in order to advance in it.
Am I missing something? Is there any way to get these jobs without first getting the (dubious) credential from universities?
You mention that a way to show ability to contribute is through "professional references and career advancement", but doesn't that also first require that you get into the company first? For the former, you need work to find colleagues who can give meaningful references, and for the latter, you need to enter the job first in order to advance in it.
Am I missing something? Is there any way to get these jobs without first getting the (dubious) credential from universities?