Wouldn't that effectively create a massive moat for high efficiency advertisers? The consequences of such a thing sound systematically perversely centralizing. Sort of like how if you were to ban all advertising tomorrow, it would strongly favor incumbents who have the most 'cached' advertising in human memory.
There's absolutely nothing wrong with that. Advertisement is pure waste for the economy. You want to make it highly efficient. If you can make it even more efficient than the free market by itself does, you should.