We have the equipment as well. (e.g Cannons, Blades or whatever) And the Professions will need equpipment of course. That is true but it was also not just one single cannon that would fight together with e.g. an infantery regiment (e.g. 50) against another army. It was a couple (e.g. 8) of them, also usually called an artillery regiment. In later centuries of course "regiments" were much bigger and were combined of many different batallions of different troops. I am not sure what we should deal with. But yes, it is a simplification - just as building an artillery regiment by a carpenter was a heavy simplification. Games need to simplify because otherwise nobody would play them if they would feel like complex reality. Artillery Professions will be able to bombard just as Artillery Units can now. The only real difference will be equipping as a Profession instead of "Building / Hurrying" a Unit (by Carpenter).