1 step, 2 step, 3 step Distribution System

1 step - Manufacturer to Consumers...
A Manufacturer develops a new part.
They study the market and competitive factors.
They decide to move forward.
They do the Research and Development. They package the part.
They market the part.
They hope the consumer calls them for the part.
They ship 500 parts to 500 consumers, one part at a time.
They must produce all 500 parts, warehouse and ship the part, one at a time.
They also have 500 customers on their accounts receivable list.
They must handle ALL warranties directly with the consumer.

2 step - Manufacturer to Mail Order / Internet to Consumers...
A Manufacturer develops a new part.
They study the market and competitive factors.
They decide to move forward.
They do the Research and Development.
They package the part.
They market the part.
They sell the part to 5 Mail Order and/or Internet outlets.
They hope consumer calls the Mail Order and/or Internet outlet and they actually order the part.
They ship 50 parts (10 parts per outlet) to 5 Mail Order and/or Internet outlets.
They drop ships 450 parts to 450 consumers, one part at a time.
They have 5 direct accounts and 5 customers on their accounts receivable list.
The Mail Order and/or Internet outlet handle warranties directly with the consumer.
NO showcases or counter displays where consumers can see and touch the part.

3 step - Manufacturer to Warehouse Distributor to Jobber/Resellers to Consumers...
A Manufacturer develops a new part.
They study the market and competitive factors.
They decide to move forward.
They do the Research and Development.
They package the part.
The Manufacturers market the part to the 50 Warehouses and the Warehouses market the parts to the 1000's of  Jobbers and/or Internet Resellers.
The Manufacturer sells the part to Warehouse Distributors (W/D) who sell to the Jobber, Resellers and Internet/Mail Order outlets.
They ship 500 parts (10 parts per outlet) to 50 W/D's.
The Manufacturer most likely does not need to "Drop Ship" any parts.
The Manufacturer has 50 direct accounts (50 W/D customers) on their receivable list. The Manufacturer does not have 450 or 500 customers that would be required for 1 step & 2 step.
The W/D's order truck load shipments and they inventory the part.
The W/D's provide for the part to be delivered daily around the country because they stock the part. 
The W/D's handles the warranty.
The W/D's handle the sales, shipping and accounting for the 500 parts.
Thousand of showcases and counter displays where consumer can see and touch the part.
What will happen to the aftermarket if all the Jobber/Reseller no longer carried the part?
Nobody would know what it does or how it works!