What programmer wants to add those things? Ads have been the bane of the internet for 20 years, how many times has a developer excitedly clamored to ruin their performance metrics, layout, security, etc with more ads? How often are programmers arguing for incredibly complex UI elements over the native (and trivial to implement) alternatives?
Programmers don't choose these things, because programmers aren't the real decision makers, it's management and business that makes the web awful.