It's usually due to incentives and the time horizon you're optimizing for. If a manager is tasked with maximizing revenue over the next 12 months no matter what, then increasing the ad load is a lever you are probably going to pull.
If your goal is to create an enduring product that will slowly grow revenue and be around forever, then you're probably not backed by VCs or private equity, or you have a cash machine (google search, etc).
The reality is that some businesses shouldn't take VC money and shouldn't get so big. Maybe a wiki farm should just be a wiki farm profitably run by 5 friends or something.
Google search has totally craptastic'd out.
Same with Amazon, it's now just sponsored spam. I just don't get why they think it's a good idea.
This all comes down to one phrase I’ve grown to hate. “It must be measurable”.
Maximizing revenue over the next 12 months is measurable.
Creating an enduring product that will slowly grow revenue and be around forever is _not_ measurable.
So, all these big brain MBAs end up forcing myopia on everyone below them because number go up. They seem so proud of themselves to have mastered inequalities.