Earlier quoted context omitted.
If content providers knew that there was a large chunk of users they'd be excluding by choosing the DRM option, they would be less likely to choose it. Firefox may be only 20% of web users, but that's still a lot of revenue to leave on the table if we can rely on firefox users to stick with firefox. I don't know whether or not we can - apparently, Mozilla is worried about it. The best option might be to sink this dev…
"Content is king!" Have you never heard that before? You say Mozilla should figure out what will draw users from other browsers, but you've outlined what will draw users from Mozilla to other browsers. In the end, people want content. The content providers have more control. If 70-80% of the browsers already support the DRM they want to use, the other 20-30% will follow or be left out. Which is exactly what happened…
All of that said, yes, of course this is something that will serve as a draw for users away from Mozilla. And yes, of course Mozilla might not be able to find something else that can serve as a better (or even comparable) draw that will not compromise their principles at least as much. I'm not casting aspersions at Mozilla and saying "Gee, they're dumb, why don't they just...". I'm saying "It would be better if they had found X" where I'm not at all sure such an X exists.