I agree, for large companies, referral makes sense.

But they were quite clear they want to get involved in seed stage and for that, referral-only is another way of saying "innovation, but only where it comes from certain connected people in a few places". Innovation is occurring everywhere and yet it languishes. It needs people like Marc and Ben. If they are serious about seed funding (and they have been and they should be), they need to set up a more indirect process as well.

I would think the opposite. With large companies there's a track record and probably enough visibility that the investor knows of their existence and could approach the company directly. Look at the way Fred Wilson works. It seems like he often starts by trying out the product before he knows the team(although he may spot them through his own web of connections).

With smaller investments, there's so many, it seems clear that there needs to be a filter to what you see. From the outside, it might seem like you need to be on the in-crowd in order to get a referral, but there are actually plenty of ways to work your way up to that referral by impressing people on the periphery.

One of my friends just took (or maybe is just about to take) money from Marc and he started out as an unconnected founder. But he worked is way into the meeting by impressing a series of people. The process, though, took two years, went through at least three levels of filters. So start by impressing the people around you. If you really are impressive, they'll introduce you to more people.

However, if you have an idea, nobody will vouch for you, and you need money now, then you're probably not going to get money even if you could get a meeting with Marc.