Actually, it's more likely because 80+% of Google users couldn't (and probably still can't) tell the difference between the advertisements and the results:
This is absolutely true. The background colour is slightly different, but on my laptop screen that's hardly visible at all, unless I tilt the screen at an extreme angle[1].
I have to say I kind of feel cheated by that trickery, every time, and it is one of the reasons (though not the most important one) that I use Google much less recently (in favour of DDG).
[1] no I'm not particularly happy about this screen, the rest of the machine is great but if I had known it would be this bad I might have picked a different model (I got an Asus EEE 1215B)
I've seen pages where the Text Ads have the same Style as the overall page. The only thing that sets the Ad apart is a small grey text 'Ads' or the like.
I've may have seen far more of such pages. But obviously i can't tell since they're near-impossible to spot the Ads.
The trend is keeping things "by the book" from search engines point of view, And manipulate humans in subtle ways
by confusing contents and ads.
I have to say I kind of feel cheated by that trickery, every time, and it is one of the reasons (though not the most important one) that I use Google much less recently (in favour of DDG).
[1] no I'm not particularly happy about this screen, the rest of the machine is great but if I had known it would be this bad I might have picked a different model (I got an Asus EEE 1215B)