Harvard Business Review just shook down what it calls the myths of great companies: the things we all think the very best companies to work for do all the time. Curiously, none of the myths it examines include money. Hopefully this means it isn’t a myth that the best companies pay well – and hopefully you and I will find this out through personal experience.

If that’s an odd omission, the five points that are included are interesting. Here’s number 4, which is one I particularly want to talk to you about.

Myth 4: They Hire for Cultural Fit

Organizations no longer select job candidates solely on the basis of their skills or experience. They hire those whose personality and values are consistent with their company culture. Among the more vocal proponents of this approach is Zappos, the online shoe distributor. But lots of other companies have extoled the virtues of hiring for cultural fit.

The idea holds intuitive appeal: When employees share similar attitudes, they’re more likely to get along, and more likely they are to produce. Right?

Not necessarily. There’s a point at which too much similarity can stifle performance. For one, similarity fosters complacency. We get stuck doing things the way we’ve always done them because no one is challenging us to think differently. Similarity also breeds overconfidence. We overestimate the accuracy of our opinions and invest less effort in our decisions, making errors more common.

In a 2009 study teams of three were asked to solve a problem with the help of a new colleague who was either similar or dissimilar to the existing group. While homogenous teams felt more confident in their decisions, it was the diverse teams that performed best. The newcomers pushed veterans to reexamine their assumptions and process data more carefully—the very thing they neglected to do when everyone in their group was similar.

5 Myths of Great Workplaces – Ron Friedman, Harvard Business Review (5 March 2015)

Read the full piece for a little more on that plus the other other apparent myths. But I’ve seen this business of cultural fit and it’s been less about slotting you in to a similar environment than it has been about bosses hiring people who are like themselves.

If they do that and their new recruits also only hire people like them, in ten minutes you’ve got a whole company of boring white middle-aged men.