I'd add that, if done well, it humanizes the company. It tells us something about the author, and you don't get that in other forms of advertising. Fogbugz is

I'd add that, if done well, it humanizes the company. It tells us something about the author, and you don't get that in other forms of advertising. Fogbugz is just another company, but Joel took the time to write (well) about it in a way that was interesting, relatable and smart. It made you believe that the products they make are interesting and smart. Paul Graham did the same. YC was humanized via his essays (which didn't really talk about YC.) Patrick MacKenzie made a business making bingo cards, but look at him now. Fundamentally people do business with people they like. Writing stuff down allows enough personality to come through to give readers "someone to like". Of course writing quality blogs takes a skillset lacking in most businesses. So yes, there's an element of cargo-cult, in that the result requires more than "we have a blog". Good blogs are enormously valuable- but most blogs are not terribly good.