yes.
it's to increase the chance of them being tasked as a target in strike mission. You'll be assigned more warehouses than parked boats, which the game really doesn't support (as in port targets). These are fixed targets, what will always appear within the years specficed by their data inis, start date in the _types ini, and even specificly listed dates in the _targets.ini.
Think of this logically ... a cargo ship in port is full of what????
thats, "goods and wares". Therefore, it's a floating storage building for ware, ie: a warehouse.
Tankers in port are full of what????
petrochemicals, most usually oil (crude or refined). Therefore it's a floating oil tank, ie: fuel_storage.
So, in the end, these have nothing to do with what your trying to do -- increase shipping traffic in the sea lanes