The reason they do it this way is because it is much easier to evaluate with confidence the people who come through their network. When sizable money is involved it is really the only way to invest. That's the same reason most people would not send a wire to a "long lost Nigerian relative" - the trust in the people on the other side of the table is low.
That's just part of the game. If you want investment from the top tier find a way to get on their radar through their referral network.
Of course the exception to the rule is to build insanely strong traction, revenue and visibility - via either bootstrapping or a handful of angels. Companies like Storm8, 99designs and a few others would fall into this category. The trouble though is that in many competitive markets the odds are against you reaching that position. If a competitor does raise significant resources and uses them to seize advantage in the marketplace your window of opportunity might close real quick.
That's why it is not necessarily a bad thing that it is Good Fella business. Just figure out how to navigate the system and use it to your advantage.
Be a pragmatist!