In my own words: consumer startups more and more have this very interesting "lightning in a bottle" effect where sometimes they take off like crazy and sometimes they just don't. I give full credit to the teams that figure out how to get the flywheel spun up, but it is also important to realize just how many highly capable founders are hard at work trying to get traction who don't. There are a lot of really excellent founders pursuing consumer ideas that just never work -- that's why companies like Yahoo and Google and others can do so many acquihires. So, if we have the theoretical ability to invest in a given category -- remembering that we can only make one primary venture investment per category -- in either the A or B round, we find it often makes sense to let other firms fund the A rounds before anything is proven and wait to see the early signs of lightning and then step in hard at the B. The end markets are so large for the winners that the investment returns in the B can still be outstanding, and we can still offer a lot of useful help to the companies at the B stage such as talent sourcing.
In contrast, enterprise startups are much more (take your pick) tractable, execution centric, brute force, predictable (as startups go). If you back a killer founder with a great engineering team, with a great idea, into a big market, the odds are high that magic will happen -- a very interesting product will get built, early customers will adopt, and value will be created. In other words, the link between founder/team competence and success is more direct. One thing that helps a lot is that whether the product will be adopted by customers or not is far less of a mystery -- you can simply go talk to the likely customers ahead of time and they will give you a very good indication. That plays well to our market development program where 1,200 big company management teams are coming through our office every year -- we ask them what they think about new ideas and they tell us. So here, backing the A round when possible makes more sense.
None of this is religion -- we still do plenty of consumer A's and enterprise B's. We just think it's useful to talk about these things in public so that entrepreneurs know before they come see us how we are thinking about things -- it optimizes their chances of getting to the right outcome with us (whatever that is).
How about asking BigCos their top pain points once in a while? That would be a 1200x treasure for current/future entrepreneurs.
Whereas the enterprise ideas are mostly engineering - or rather the art lies in really understanding the customer and the domain, which is relatively straightforward for the great enterprise entrepreneurs, because they are already so deep in it and you can easily go talk to the customers one at a time and learn what you need to know to predict success or failure with pretty high confidence. Not easier but different.
These are all gross over generalizations of course. I think of this as a framework for thinking - one of many - not a literal description of the truth in all cases. One lens.