The iPhone can do three-second exposures free-handed, and have them come out pretty sharp without even trying to hold the phone still. That is not something you do in postprocessing.
That's really the point. If all I had was a phone camera, I would be glad for all this software support. For all the times I have my DSLR, the 10x bigger sensor obviates the need for all of that.
Like, you're literally describing all the extra effort and gear you have to have to do this on your camera. Wouldn't it be better if you just... didn't need any of that?
I've seen some of the absurd lengths people go attaching things to their iPhones just to reach parity with an entry-level DSLR and a few attachments that cost less than the iPhone rig with the cost of the camera included. I looked into the lenses on the 12. The longest is a 35mm equivalent of 85mm. I would need a grip add-on and a lens clip with no image stabilization just to approach the stability and reach of my 70-300mm lens on an APS-C sensor. That's just for wildlife photography, and not even the longest lens. Most serious wildlife photographers go for a full frame and 600+mm primes. And that's just one use case served by the photography platform that "big cameras" are.
You don't know what you don't know and it shows.
The argument is that DSLR software is lagging far behind what an iPhone can do. The point is that DSLR software needs to improve, not that you should use an iPhone.
Capture One/Lightroom and Affinity Photo/Photoshop will have those features with higher quality long before they reach non-phone cameras. They work with the raw data right off the sensor. Nothing done with the limited power of an on-board processor will beat a good raw processor in pulling a good photo out of subpar conditions.