A side note here the Domino bits screw on to a male threaded shaft so they are hollow on the screw end and they are just less than 10MM in diameter so they might fit in a 10mm collet. And those bit's are designed to cut in a sweeping arc, they may not cut as well or last as long cutting in a straight line. The cutting end is rather unique.
I understand that all of this could be done with a plunge router but some of us prefer to be spending more time actually building something other than jigs. ;~) I think a jig is great if it saves you time.
But seriously have you got a jig that will allow your plunge router to cut these? Keep in mind the bottoms of these mortises are 27mm from the very end of these pieces of wood, not the surface that the mortise begins. And the 5mm bit will not cut a 27mm deep mortise. The bit has a shoulder that prevents this deep of a plunge cut. The mortises have to be cut "after" the 1/2" deep and 1/2" wide section of material is removed.
Then those mortises have to match and index properly with these.
Now, for another example. I am going to assume you have a biscuit cutter. I'm also going to assume you have cut hundreds of slots for biscuits. Before you bought your biscuit jointer did you seriously consider cutting that many biscuits slots before you bought it? Did you consider or actually build a jig and use a plunge router to cut that many slots before buying the biscuit cutter?
If your goal is to build 6~8 pieces of furniture for your home in a decade your suggestion makes a lot of sense if you have the skill to design the many jigs necessary to make the multiple types of mortises that you may need to cut. In the last 4 years I have built 11 large pieces of furniture for our home and never would have had the extra time to build the other 25 or so pieces in the same period for my customers. With the Domino my production has probably increased 500 percent. And Sketchup plus Cutlist Plus have been significant times savers too.