No, I think they want it to go away so that it's out of the system entirely. This way crafters benefit from this as they need to make more items as it takes item out of circulation. Gatherers also benefit from this as the crafters now need more items to keep up with the demand.

I think if Crafters and Gatherers use their gear it will likely gain AP just like it would for an Adventurer and could be consumed for Materia. All that Gatherers do is obtain the catalyst which is used to bond materia to an item. All crafters do is slot the materia into the item. All three likely can consume items to become materia.

All it says is that when you use armor and weapons (probably also tools) it gains AP and can eventually be turned into Materia. Nothing says it won't work for Gathers and Crafters too.