A milestone is a milestone is a milestone. Similar complaints came as PS4 cleared early milestones. I also then objected to the complaints and said it still cleared the milestone. Whatever detractors say. And there is no way denying that achieving a number the WiiU needed 5 years for is a feat.
3ds done the same thing and keep in mind it sold SLOW early on and took a few months to take off. It's typical of a Nintendo handheld, not a milestone.