Cultural matches are important and they drive more decisions than we're all comfortable with. The truth is, we often like to hire, promote, or buy from people who fit a certain stereotype. It's essentially a cargo cult around what successful startup people are expected to look like, and the most uncomfortable thought arising from that is not the number of founders who "wrongly" received funding, but the number of hopefuls who never got the chance.
However, taking the time to really get to know and appreciate a startup person is not something that can reasonably happen a lot when you're in contact with customers, the press, or even your own employees - so the (bad) impression a team makes while interviewing for an incubator or fund raising does tends to follow them around.
People can and do change their appearance to match other people's expectations - and it's a proven, working method of upping your chances. Learning how to interact better with others, while certainly painful, also helps and is more often than not necessary to become successful.
We're often distracted by the Zuckerbergs or Jobs' who are abrasive and embody their own don't-care-for-anything style, but the ugly truth is that those guys got so unbelievably lucky that they never needed to actually work on themselves.