Comment by upupupandaway

As someone who ran part of their fulfillment network, I say you are completely off the mark here. Their network is the best in the world bar none. In addition to marketplace, 1P, and FBA, there are many other cooperation models where massive companies that appear to have their own distribution centers actually use Amazon's network (even co-located for some warehouses/sort centers).

There is no 3PL or other warehouse companies (many of which use Amazon's anyway) there are better than Amazon. Maybe Walmart gets close. For the case you mentioned (OMS integrations), this absolutely does NOT mean that they handle shipping. The aggressive majority of those vendors just uses FBA anyway.

If you're building your startup on the principle that Amazon is "a sales channel only", then I wish you well but you will fail.