I actually feared it is about something like that.
From my point of view not thought hard enough through entire process. today you care about MRP run and requisitions. Once the material arrives and sits somewhere in your warehouse, nobody knows how much steel of 20 mm you have in stock., because you just see a number for the total quantity of all steel in any mm size.
And MRP can only take care in case of a make to order scenario. In case of neutral stock in a warehouse, it is totally unknown which size has to be requested.