Hmm, no. Considering them an ad company helps to keep what they do for money on the forefront. Trying to push it down as some ancillary activity makes sense if you're marketing for Google, but not in any other situation.
It's difficult to tell whether you're a troll or just very attached to a single perspective. Yes, it makes sense to look at Google as primarily an ad company in some contexts--for instance, attempting to understand their business model. In other senses, Google has done a lot to distance themselves from being just an ad company, diversifying in image, product, talent, markets, and company culture. Probably more, but I don't know too much about the intricacies of what Google actually innovated on. Just by doing this, yes, I do think it is inherently dishonest to group them with other entities that do just resell web space. And I do not think that Google would cease to exist if people boycotted advertised products tomorrow, either, because their grasp of tech culture is so strong. People will always need analytics, retargeting, and profiling, so reducing an entire company to advertisers is downright insulting. Just the competition to ios alone has irreversibly changed the future of smartphones, mostly for the better.
Hell, just the market value of Google's brand is enough to distinguish them. You cannot buy that trust, you earn it by providing more value than an advertising brand could.