While you're absolutely right, there's still one problem: There aren't much, if any, advertising providers with ads as accepted and unintrusive as Googles AdSe

While you're absolutely right, there's still one problem: There aren't much, if any, advertising providers with ads as accepted and unintrusive as Googles AdSense... Not to forget their huge portfolio of ads that will fit almost every context - so yes, AdSense is the go-to provider for most.