The other is "If you have an iPhone you too can make such a video". Which is what anyone who isn't affiliated with the film industry (aka 99% of the population) might think, especially if they didn't see the behind the scenes.
I honestly don't think it's a reasonable takeaway for anyone who is at all interested in creating highly produced video with their iPhone. Even if you're an absolute beginner, it's abundantly clear that these Apple videos are serious productions.
It's not significantly different than hearing that an accomplished journalist wrote a column on their iPad, or a successful entrepreneur manages their schedule with their iPhone calendar, or a famous musician uses GarageBand for songwriting (or even full production).
The point in all of these examples is never that you can accomplish these things with an iPhone anddon'tneed talent, creativity, years of practice, other gear, etc. The only point is that the iPhone is not a significant limiting factor on the quality of results you can achieve.
I think there are 2 parts to this:
One is "iPhone camera sensors are competitive with commercial offerings in some cases". I think this is what Apple was trying to go for with the entire thing including the behind the scenes.
The other is "If you (edit:just) have an iPhone you too can make such a video". Which is what anyone who isn't affiliated with the film industry (aka 99% of the population) might think, especially if they didn't see the behind the scenes.
"Shot on iPhone" hence has 2 perspectives.