You can see it in larger dSLRs when you get blurry images at F/8 and smaller.
I have nearly 40 lenses for 35mm, medium format and 4x5, not a single one of them is showing the effects of or hitting the limit of diffraction at F8, not my Leica 35mm 1.4 aspheric FLE, Zeiss 50mm F2 Milvus, Hasselblad 100mm 3.5 CFi, Nikon 20mm 1.8G, Rodenstock 135mm 5.6 Apo Sironar S, etc.
I get where people are coming from here on all this but as it stands, the incredibly unique if not secret sauce like edge effect of natural sharpness that the iPhone has presented ever since the iPhone 4 is legendary for a reason. What Apple has done here with the 7 plus will probably be astounding, even if it is a little frustrating to those who rightfully insist on passing on the bigger phone.
If you were to look through my past posts, you would see to that I have never been interested in the larger phone, can't possibly see it being anything but in the way while working or playing. But for a host of reasons, I have changed my mind and besides this new camera system being one of them, I can no longer deny that not only are my eyes at 49 years old getting weary after 30 years of professional photography, the eyes of some of my editors, art directors and other clients are too.
Showing work to clients on the bigger phone is a no brainer for marketing, making killer new images that WILL make me money on the same phone is simply brilliant.
I have ordered the top of the line version of this phone ( 256GB ) and will not regret it, I just have great instincts that way. I do hope they offer the same great camera hardware options in the smaller form factor though, I 100% agree that it is BS to always be stuck with getting the bigger phone in order to max those specs out.
Hopefully that will change next year.