Admittedly, there are types of business that you certainly need to demonstrate traction in order for folks to get interested, but traction should be a symptom of the value you are creating rather than the root cause. If you are building a business that is driven by network effects (core focus of NFX and something I look for in every startup I work with), than setting the conditions in place for those network effects to take hold is much more important than revenue. There are also categories that are “hotter”, more defensible and/or harder to build network effects than others. Investors will be willing to take more risk (i.e. go earlier for those) than they will for others. For what its worth, more than half the startups I’ve funded have been pre-revenue.