Mov NCOs are trained IATA DG by air and have been for many years. As for who's more qualified - irrelevant. The 2 jobs have different roles and by having ALMs trained as well, we have an additional person who can check. Additional checks = safer aircraft.
Movers do not work for ALMs. Again, different roles. The mover works for his team leader (mover) and prepares the ac (loading, paperwork etc). The ALM is responsible for the load in flight and will accept it from the movers.
Certain jobs need NCO rank to provide authority, ALM is one. He / she must have the authority to control his / her passengers.
Clear?