Perhaps, but how do we measure that?
I was surprised to learn recently that advertising for the past century has only grown at pace with GDP, i.e. it has continued to be about 1.29% or our economy: http://www.bloomberg.com/bw/articles/2014-03-03/advertisings...
But it's still possible that advertisers are buying an increasing percentage of our time and attention. I would love to see a study that attempts to measure that, though it sounds like a tricky task.