About 4 years ago I took an excellent load training class mostly designed for those wanting to become a broker.
One of the main classes is how to price a load for the consignor (the broker's customer) when asked for a rate to move a load. One of the ways of doing this is by posting a dummy load, so carriers will call in and give a price for what they will run the load for. After 3 or more rates are submitted you, then take the average add 12% or more for the brokers cut, and this is the price you give the consignor. I would assume this is a common practice among other brokers as well.
This is one of the causes of Ghost Loads on load boards. Loads you call on that rarely ever mature to real loads.
New brokers just starting out without the funds to pay for more expensive reliable services are well known for posting Ghost Loads. Some load boards gave great sign up discounts to their load board after completing the load training class where they then practice getting rates for Ghost Loads.
When comparing load boards, it's not about the number of loads posted, the focus should be more about the quality of the loads being posted.
Don't get Ghosted