OK, perhaps I should qualify that with "assuming the camera has a decent quality sensor". Although since Apple and Samsung do, that seems a bit redundant for a discussion about spec warriors. If someone is going to claim that their Nogood Phone Ltd QLX8732 with the 897MP sensor that produces images worse than 110 film is competing with the 5S and the S5 then I can't help them.
The fundamental point being that 98% of photos taken today are only ever seen on Facebook or similar, and those services downsample images to 0.25 - 1.2 MP at most. Start with a good quality 8MP image, crop it to 6MP, submit it to Facebook as a "high quality image" and you're down to 1.2MP. But even if you want to make prints 6MP generates an excellent quality 5x7 and a good quality 8x10 for all ordinary people.