There are a few reasons. For large institutional investors, they have a responsibility to stand behind their decisions: saying "I didn't really understand what

There are a few reasons. For large institutional investors, they have a responsibility to stand behind their decisions: saying "I didn't really understand what it is they were trying to do, but their metrics, whoa!" does not stand up. And a lot of more conventionally-minded investors look to truely understand what a companies value proposition and product is. If you could invest earlier in Pinboard, or a company which has found a revolutionarily cheap way to manufacture toilet paper - you know which one has a more steady and obvious demand, right? Although SV, the YC/VC world, operates very different. Just a few ideas.