All new boats do NOT suffer from that problem. However, if that filter was installed incorrectly it may be full of fuel (essentially a clog) or if the system was grossly overfilled the canister may be full of fuel for that reason, too. This charcoal "EPA" system (it's part of the mandated vapor collection system) is not brand new, either, it's been around for a while, now.
I know you said it's hard to get to, but if you wanted, remove it. BUT, a properly installed (and functioning) system "should" allow you to fill your tank at a normal rate.
I would not accept the answer you were given - it is not "normal".
FYI... it's basically the same thing as in a car - and we don't have issues there.