Apple certainly does sell more phones than Nokia. And that probably isn't going to change... at least not in the foreseeable future.
The difficulty comes when people automatically make the assumption that because something is used the most/sells the best means that it is the best. A lot of the population will assume that because more pictures are taken on the iPhone than any other smartphone that it somehow must also be the best. Certainly Apple has been okay with this misconception because when given a chance, they will talk about how much better their camera is than the previous generation, or another particular product. A certain segment of the public will take that to mean that the product is the best. When, in this case, that doesn't reflect reality. (Certainly happy Mac owners would not want to accept the belief that somehow because Windows outsells OS X by a wide margin that somehow it is better, but for whatever reason that has happened historically with the iPhone.)
My friends with iPhone 5s seem to all believe that they have fantastic cameras on their phones. (And I think they believe that because Apple has been selling that idea.) That is, until they see pictures coming from my 920. I think they feel a little bit betrayed. They've been lead to believe that they're carrying around great cameras, when in reality the camera in the iPhone 5 are probably the worst of those amongst premier products. Cameras in the Lumia 92x series (certainly the 1020 as well), Galaxy S 4 (maybe S III), and HTC One easily outperform the iPhone in nearly all situations. Yet most iPhone owners aren't aware that they've been sold short. If they don't care, fine... but if they buy an iPhone thinking that they're getting a great camera, a certain amount of disappointment is probably inevitable. And nobody likes to be lied to, even if that deceit is inferred rather than explicit.
It isn't wise for Apple to tout the quality of the iPhone camera when pretty much everything else in its class outperforms it handily. (What would you say to Nokia if they started bragging about how many apps Windows Phone has?) Sooner or later their customers are going to pick up on the fact that they've been misled, and that isn't very good for maintaining a relationship with a customer. Push the real strengths of the product, not its made-up ones.