What Explains the Expanding Use of Wholesalers

Short Answer

What explains the expanding use of wholesalers?
Delivery time between the producer and the consumer is faster than it used to be.
Wholesalers have a bigger distribution network.
The cost of retail space has risen, thereby creating pressure to limit storage space in retail outlets.
The development of a good truck distribution system and highway system permit quicker delivery of ordered goods.
The order-cycle time has declined.