On Tue, 21 May 2013 10:37:04 -0500, -MIKE-
Are you saying that even the Festool doesn't get the alignment perfect?
Or is there some aspect is M&T joinery technique that makes it
beneficial to have a sloppy joint? I haven't done a gazillion loose
tenon joints like you, so I honestly want an explanation for this.

No, we're saying that you don't understand the type of joinery that
can be done with the domino.

The mortises are cut perfectly on the vertical plane, but can be, if
desired, cut wider on the horizontal plane. The wider (if desired)
horizontal mortises permit some sideways adjustment, yet still enable
wider flat surfaces to fit flush and be properly glued.

Think of it as being similar to a biscuit that can slide in one
direction, but doesn't slide or move in the perpendicular vertical
direction.