Of course, since it's not your work that is being mis-appropriated, you're free to look at it another way :-)
Sites want as many unique visitors as possible because larger sites get more attention from advertisers, it permits better frequency capping, and enables better segmentation of audiences. Even though they get paid per impression, larger uniques tend to allow for higher CPMs.
Separately, it's worth considering that many writers are measured on metrics: uniques, minutes, shares, comments, etc. In some places, they might even get paid on such performance (I think Gawker did this). When content gets copied, the writer can be deprived of such credit.
I was wondering whether such ad-blockers exist. Searching for one and installing it now.
† Just within English we have words like "cleave," that are widely accepted as meaning both "hold on tightly" and "separate." And in Spanish, we have "dame" which means "give," while in Japanese they use the same word to mean "don't do that." Can we declare the Spanish or the Japanese to be wrong about what that word means?
When they are terms of art, they frequently do.
Basically, what I'm saying is, the fact that you and your friends use a word a certain way doesn't automatically invalidate other people's usages. It is true that mattmanser's use of "steal" was not legally precise, but neither are many colloquial uses of the word ("It was such a steal at $5!", "He's stealing third", "Great artists steal", "His identity got stolen", etc.). You would be right to object if he had been raising a legal argument based around the concept of theft, but he wasn't, so it seems overly pedantic to me.
You are getting close to the point here.
Why does a term of art have a specific meaning to a practitioner of that art? Answer that, and you will have determined why words have meanings in any context.
Borrowing words across fields (because of similarity) can cause confusion. One person may assign a meaning from a different field than the other interlocutors are using.