One is that to pay more for an ad the advertiser wants to know which user explicitly interacted with it or saw it. So non-intrusive ads on the sides of a UI are by far lower in value during sales.
The other is that the one way to increase interaction and value is to prove that the ad is the only thing the user was exposed to, ie. eliminate everything else.
So what we get today is an entire aesthetic and de-cluttered look. Even when you pay for premium the design is still made so that the machine can read into what your eyeballs are up to.
There are two things that pop into my mind here.
One is that to pay more for an ad the advertiser wants to know which user explicitly interacted with it or saw it. So non-intrusive ads on the sides of a UI are by far lower in value during sales.
The other is that the one way to increase interaction and value is to prove that the ad is the only thing the user was exposed to, ie. eliminate everything else.
So what we get today is an entire aesthetic and de-cluttered look. Even when you pay for premium the design is still made so that the machine can read into what your eyeballs are up to.