[PointerReaper]

In my line of accessibility work, I find QA fills the role of testing to educate. If the engineers don't have the experience, looping issues into the backlog, gives them the experience to train up the skill set. They might have had verified experience before hiring, but getting team collaboration helps mature new people or smooth out the rough skill sets of a dev who might be awesome in one particular area but meh in others.

I suspect this could be the case for any subject matter expert where the skill set is viewed as fringe or not expecting the team will be required to have that exact knowledge before hire.