Which is why most consumers used fairly crummy fixed-lens cameras with fast film and were perfectly happy with digital cameras with ~4MP effective resolution. You do need a whole bunch of resolution if you're printing to double-page magazine spreads, large-format fine art prints or billboards, which is why professional photographers (other than photojournalists) were relatively late adopters of digital cameras.
>And if you're talking about stops of dynamic range, print has always been less than a screen.
At your local photomat, yes. A good giclée print has about 11 stops of dynamic range. A normal 8-bit LCD has about six stops of dynamic range and a really good OLED has about ten stops under ideal viewing conditions.
My broader point is that pretty much all modern cameras are more than good enough for 99% of users. It's a tiny minority who will actually see the benefit of better cameras in the images they produce. Most people will only ever notice an improvement in resolution if they're pixel-peeping in Lightroom and will only notice an extra stop of dynamic range on the histogram. If you go out and buy an entry-level DSLR with a kit lens, you probably won't get noticeably better results than just using your iPhone. That's a good thing for consumers, but a bad thing for camera manufacturers.
A 4x6 print didn't have crazy high resolution. They usually use 1800x1200px as input resolution (~2.2MP). Your iPhone X is actually slightly more detailed (2436x1125=2.7MP). And if you're talking about stops of dynamic range, print has always been less than a screen.
But if you want a photo to look crystal-clear on your iMac's slide show screen saver? That's 5120x2800px=14.3MP. It allows for stunning detail which consumers just never had access to before. (Even the iPad Pro is 5.6MP, more than double a traditional photo.)
But the real advantage, of course, in both megapixels and dynamic range is in post-processing: you can crop to the quarter of the photo that's interesting and bring out the detail in the shadows and it's still high-quality enough to use as an eye-catching retina-resolution header for your Medium post. Remember, phones don't have deep optical zoom lenses, so megapixels have to do that job instead.