Because chrome will too for exactly the same reason Firefox has, but chrome comes with the bonus of tracking the user's activity, creating profiles, and sending pseudonymised data back to google, which with google's analytics and profiles, is as good as personally identifiable to them as they can just link it to maps, gmail, youtube, etc to get a full profile.
Don't you think it's a bit odd that the premise is to "trick" users into using Firefox by luring them in with promises of Netflix support? What's the point of this, and what precedent does it set? These are the issues we need to think about, rather than just saying things like "oh no Mozilla is losing all it's users" and other silly doomsday predictions.
If you have some magic trick for doing it, go ahead.
A majority of people are stupid. They don't care about their privacy, they use chrome because google advertise it, they leak data everywhere they go, and either don't care, or are imbecilic enough to believe "If you've got nothing to hide, it doesn't matter".
In a way, HN acts as a reality distortion field if you get the bulk of your news from here, because people here are likely to make well researched comments with thought behind them; which makes it easy to forget that a lot of the world's population is very stupid and/or apathetic about most issues.