What's worked really well for us is not having the DBAs as gate keepers, but rather having them as guardians and experts for devs to rely on.

Our DBAs are the first line of defense when a DB starts to struggle. They crack the database open, see what's going on, and troubleshoot and sometimes fix the problems. If it's just a simple stored proc change or table change, our DBAs are empowered to go in and fix them. If there's a code change needed, they work with the devs to fix the code.

But by and large the devs still write most of the queries and tables. We as devs get DB training, but we also have a very open door policy with the DBAs so the devs can lean on their expertise and ask advice before sending stuff out. Our devs get a much better sense of "This seems like it could be expensive, let's talk to the DBAs and see what they'd suggest".

It's worked great.

I think any company would benefit from this sort of subject matter expert employment.