Originally posted by VolOpt:

Ingots on the other hand make zero sense
Since the player has
1) Already transported the ore to some level of base/outpost by way of foot/cart or boat.
2) put in the effort to smelt/purify them (read: did the thing)

Where it extra falls apart is that you can then travel with armor/weapons which are just the purified ingots reshaped into armor/weapons.

From a game mechanic perspective it might make sense, as you can make a portal and smelter at the mining location.
Run through the portal and any enemy stops attacking that location, and transport ingots instantly from the mining location to where you want.
It negates the overencumbered mechanic, and only requires a little planning beforehand to do.
But lore wise, ye it makes no sense to not transport ingots through portals.