Here's how it works. The blank DMM disc is a stainless steel disc with copper electroplated over the face. The back side is bare stainless steel.
The grooves are cut into the copper coated disc. This disc now serves as the mother. You can play it and then make direct stampers from it ("shells"). Make as many stampers as you want from it (as long as you don't damage it).
When you're finished with that title, strip the copper off and put the stainless steel disc back into the copper electroplating tank and make a new blank DMM disc.
As you can see, there is no silvering and no need to make a mother because the cut DMM disc already serves as the mother.
Yes, you can make a stamper directly from a lacquer disc but if you damage that stamper you can not use that lacquer disc again to make another stamper. This is what our American friends call "one step plating".
The first electroform made from the lacquer can be used as a father (or "master") to make a mother, etc or it can be converted to a stamper (a "convert"). With DMM, you can use the copper disc again to make another stamper should you damage the first one.
In so-called "two step plating", a mother is made from the father and then the father is converted into a stamper. If the stamper gets damaged, you can go back to the mother and make another stamper.
I don't know about the cost benefits but there are sonic benefits with DMM which is a whole different topic.
Most plants offer you the option of one-step, two-step and three-step plating so it depends on what you ask for. A plant that has disc cutting in-house can afford to use direct stampers ("one step") as a re-cut is not far away.
I doubt anyone would make a mother unless you paid for it when just pressing a few hundred records.
So just for the sake of clarity, let's assume you just want one set of stampers, and you are very careful not to damage them. The only thing separating DMM and regular lacquers is the silvering. I mean creating some stampers from a pair of silvered lacquers or a pair of DMM masters is essentially the exact same process?