Note they did not say "Google is now an ad company", it was "now we consider Google an ad company first", it is a matter of perception.

In 2013 it was not a commonly held position that Google was primarily an ad company.

It's neither here nor there, but it's worth mentioning that Google as a search engine was around for five years before that SEC filing. As I'm sure you remember, that was a very long time in the history of the Internet to that point. Plenty of time to build good will and ruin it later, as we saw a similar pattern with Chrome years later.

Google was routinely referred to as "one-trick pony" already by the end of 00s due to the obvious fact that 95% of its revenues were from search ads.

IMO the difference is that many people perceived it as a benign deal - someone would take money from the advertisers and use it to actually make a better product for the users. It took a while for enough people to realize that this very reliance on ads means that "better product" from Google's perspective is not necessarily better for the users.

Although by 2013, I'd say that even that was not an uncommon sentiment, especially since Google started doing stuff like this around then: https://commerce.googleblog.com/2012/05/building-better-shop...