"Let's suppose lots of people start using Windows because they don't view
proprietary software as unethical, and this compatibility layer gives them
all the convenience of running Ubuntu without the inconvenience of switching
between operating systems. Microsoft gains users, and Linux loses users. But
the libre software movement doesn't lose anything."
1.) Given windows' dominance (i.e. people buy pcs with OSes on them and that
is usually windows) it makes more sense to speak of MS retaining or losing
users (not gaining or losing).
2.) I agree that Libre software is unlikely to lose anybody who is already
signed up because of this 'innovation'. So for us it is gaining or not
gaining (not gaining or losing).
So winning for them is retaining users and us not gaining those users.
Winning for us is windows losing users and us gaining those users.
So when you say we won't 'lose' anything, that is not true. We can lose users
we would otherwise gain.