I agree no phone can take photos like a DSLR but the fact is you will miss so many photo opportunities because you have to plan it like an event. Just today I saw a rainbow and it was probably the best rainbow I've seen. It wouldn't still be there if I had to drive home to get a camera. When your child takes their first steps are you going to pull your phone out of your pocket and take the video or picture or say "hold on let me go home and get my DSLR". When you see a cute animal outside are you going to say "stay right there I need to go get my camera". DSLRs are totally awesome and $600 isn't out of the price range for most people. The problem is you can only use it for planned pictures. Of course if it's a wedding, graduation, or maybe even a birthday party why not break out the DSLR. I personally have my eyes on a really nice Nikon DSLR that when I get the extra spending cash I'm going to get. TBH I'm sort of an old photo bug that misses 35 mm cameras.
As to the iPhone or any other smartphone being a "phone" is just silly. Most people barely use their phone to make calls. It's a messaging device, computer, camera, game console, wallet, notepad, alarm clock, flashlight, etc. It might not do those tasks as well as a dedicated device but it's the device that's always with you.