I can never figure that out, but lots of people do it.
My logic in removing it-
A plain one costs $2-$5.
Would I sell ads on my car for $5 for 2-10 years? No.
So, if you have one, what’s the story 
I still have a dealer license plate frame on my pick-up. I haven’t been able to locate an “American by Birth/Southern by the Grace of God” license plate frame yet.
I think a lot of people leave 'em on when they’re relocating, as a subtle way of identifying their home town to others in the know. I get a little bit homesick when I see a license plate frame for a Buffalo-area dealer surrounding Colorado tags. Then again, the five or six Buffalo Bills or anti-abortion bumper stickers that grace the back end of a car is also a dead giveaway of Western New York heritage.
Inertia.
Sorry, not meaningful, but honest answer.
To change it I’d have to hassle with the auto supply store, holders that never match up with 1.) the openings or 2.) any screw I have lurking around in jars and 3.) worry about it.
Move on, hopelessly female non-car identification subject here…it’s just more hassle than it’s worth. Maybe my indifference, but I just don’t care enough to bother with it.
Aggravating, sneaky, opportunistic advertising on a huge hunka expensive moving metal, but I just want it to get me from point A to point B.
Veb