you are not right
Reasons: You have small guns P90, XL, ... big guns who have minigun, avanger, LSW, M60.. energy laser gatling... T4 like Boozar, Vindi...so you are not right. . The choise is more than this, but this is people mostly use in battle, and caravans(others are preaty useles choise). Also MRD,BRD perks work for every weapon, pyro perks only on two.
. I think buster is also specialised build in same way like pyro(like every build here)... maybe flame pistol is not necesery(because solar), but why not T4 for pyro and coctails to work with pyro perks??
Even why not legend with fire gecko breath to work with pyro? I not see good argument in your opinion why not.