>I don't know a single web dev who tests on Opera anymore
You don't know very good web devs then. By far the easiest path as a developer is to develop for opera, then test the rest. You end up with far few problems that way. If you develop for firefox or chrome it is easy to write a bunch of stuff that works in that browser, but not in the other, and then you have way more work dealing with fixing it. Opera is strict enough that if it works there, it is almost certainly going to work everywhere else (not old IEs obviously).
You don't know very good web devs then. By far the easiest path as a developer is to develop for opera, then test the rest. You end up with far few problems that way. If you develop for firefox or chrome it is easy to write a bunch of stuff that works in that browser, but not in the other, and then you have way more work dealing with fixing it. Opera is strict enough that if it works there, it is almost certainly going to work everywhere else (not old IEs obviously).