I rather think it's because a lot of people don't really know how. Like a lot of others, I don't mind advertisin in principle; indeed, I think they have utility and sometimes click on them because I'm actually interested in what's being sold.
...BUT not the ones that float in when I've already started reading the page, or that take over my screen when I unwittingly roll over them with the mouse (and obscure their close button), or that feature hot pink silhouettes of people dancing in a .gif loop to sell me car insurance, or use what's apparently some guy's mugshot to tell me about some shady mortgage refinance scheme.
For every informative, polite, and compelling advertisement that represents a meaningful commercial communication, there are about 99 that are equivalent to being shouted at via megaphone.
...BUT not the ones that float in when I've already started reading the page, or that take over my screen when I unwittingly roll over them with the mouse (and obscure their close button), or that feature hot pink silhouettes of people dancing in a .gif loop to sell me car insurance, or use what's apparently some guy's mugshot to tell me about some shady mortgage refinance scheme.
For every informative, polite, and compelling advertisement that represents a meaningful commercial communication, there are about 99 that are equivalent to being shouted at via megaphone.