Few inputs for you based on my experiences. Trying to be unbiased as much as possible.
1. Selling/Buying a property scenario:
The number of queries i got from genuine buyers after i posted on mbricks,quickr.. were very less compared to the number of genuine buyers brokers were able to get. So I thought maybe lots of buyers don't actually log on to internet sites and are more comfortable dealing with brokers.
I also put a couple of ads on TOI. Got decent response. But nothing to beat brokers.
2. Renting an apartment for myself.
Thought I will try to avoid brokerage here. Tried searching all over internet, news papers. Nothing significant came up. Finally payed 1 month brokerage and rented an apartment.
In case of resale and rentals as of now, brokers have total monopoly. You might try to avoid it. But requires lot of effort/time and luck. More often than not, does not work.
Now some of the reasons.
If you are a smart seller, you will find brokers who will sell your house for 1%, 0.5% or even no commission. That puts the onus on the buyer. So the buyer ends up paying bulk of the commission. Similar is the case while renting.
So overall things are loaded against the buyer/renter. These are things during a steady/up market. Don't how things will be in a down market.
Despite all this i do believe a system like "nobrokerage.com" is still viable. That is because quite a few brokers do charge sellers as well. So if the seller is able to generate few good queries he might surely log on.