Culture fit just means no assholes
A lot of companies claim they look for a “culture fit” when hiring. In practice this just means “we don’t hire assholes”.
Does culture fit mean hiring people who share the same sense of humor? Or who think in similar ways? Or with similar personalities? When that 100x engineer comes along with mad skills and is incredibly nice but has nothing in common with everyone else at the company outside of work, are you not going to hire him/her because of a lack of “culture fit”?
A more useful definition of “culture fit” is whether they fit with the company’s core values. E.g. Zappos defines “weirdness” as part of their culture. However, if someone is not quirky in any way but is a great hire otherwise, would they not hire them? If they are nice to the limo driver, get along with everyone well and are functionally superb, I doubt they’d get a no.
Hiring for “culture fit” is often just a euphemism for “we don’t hire assholes”. It pans out this way because companies often have similar, positive core values e.g. humble, works well with others, determined etc. It’s rare that a company defines one trait as more important than another e.g. we’d rather hire extremely ambitious people and don’t mind if they’re arrogant. If they do, putting that into practice when hiring takes a lot more guts, especially when there’s a glut of supply in the market for talent.
I don’t think this is a bad thing. I think companies should be accepting of people with different backgrounds, interests, personalities and judge them on how they’d function on the job, and being great to work with is definitely a large part of how they’d function. But turning people away because they might not have the same personalities or values as everyone else might lead you to turn down super talented people that were just fine to work with.
Culture is a natural extension of everyone in the company. When you hire someone new, your company culture is infused with that person’s values, character and personality. This means company culture keeps evolving. It emanates from the founders and can be controlled to the extent of who you choose to hire. Nobody wants a company of assholes, but there’s also value in diversity of personalities and values,  so in the end, most companies are open to hiring different types of personalities as long as they’re functionally superb, have good character/integrity and are good to work with.
Have you seen a company where “we hire for culture fit” can’t be substituted by “we don’t hire assholes”? Has it been a contributing factor to their success?
 Perhaps diversity slows you down at the super early stages: http://www.quora.com/Entrepreneurship/Among-Max-Levchins-lessons-learned-as-a-young-entrepreneur-which-are-the-greatest/answer/Max-Levchin