From my point of view, which is largely seeing BB’s selected clips Doocy represents the “conservative” point of view, but seems more or less polite enough to wait to be told why he is wrong (which he largely ignores).
So anyone who is conservative, or borderline conservative and actually watches WH press briefings might get to see the opposing point of view. I don’t think there are a lot of these people though.
However anyone who has one of these people in their sphere though, a unwanted coworker, a family member that has sadly lost touch with objective reality, and so on, well they get a well articulated counter argument they can later use (either in actual conversation, or just to repeat to themselves while trying not to throw the mashed potatoes).
Is it really the most useful purpose for White House press briefings? I’m not sure, but I’ll bet it ain’t the worst.