>The widespread adoption of Chrome was largely driven by word of mouth
No, it was driven by having a banner in the most privileged spot of the Internet, Google.com (the most visited site in the world with 0 ads on the homepage) saying that was faster and more secure than the alternatives. In fact Firefox benefited from some free ads on Google.com against Internet Explorer before Google developed Chromium.
It was kind of both, depending on the timeline. Early on it was word of mouth, then Google saw they had momentum and they capitalized on it with the banners and aggressive marketing.
Early chrome was driven by the fact that firefox was a piece of garbage. Firefox 3 was not good software, and had an unpleasant habit of totally crashing the entire browser regularly. Your only other popular choice was ie8. Also not great.
Later Google's ability to buy installs and put it on google.com came into play, but for at least the first 5 years and probably longer, chrome was a far faster, more secure, and more reliable choice. They also pioneered the multi-process model to isolate different components of the browser.
… isn’t that banner an ad?
Yeah, I feel like in general we on HN give ourselves way too much credit in terms of our ability to drive public opinion or affect purchasing/usage patterns among the public. The idea of the “nerd-led revolution” may have had some impact in the past, but I think the days of that are over. Large corporations now know what they’re doing in ways that they hadn’t figured out in the 2000s or even the early 2010s.
The other aspect, somewhat memory-holed, was that Chrome was automatically installed as shovelware if you went to install Adobe Flash for IE or Firefox:
https://www.reddit.com/r/chrome/comments/23jnmy/why_is_chrom...
This kind of not-freely-given consent was key to Chrome's growth.