Yes, clearly that was the intent. That doesn't mean you can generalize from your proxy to the thing you have a hard time measuring.
> So ad spend is going up at the same time that the number of ads per spend is increasing, at a rate substantially faster than during their study period.
It seems like you are just making up facts.
The fact is that global spending on advertising is a fairly steady percentage of the GPD. It does occilate a little up and down, but the "exponential" growth you are talking about is merely the exponential growth of GDP.
Thus your argument that internet has increased ad spend and thus decreased happiness is false.
Addionaly, while this is also hard to quantify, the trends for cost per ad view does seem to be moving in the opposite direction. The cost of an impression seems to be moving upwards, not downwards.