and sometimes it's because you're an idiot who took off into the bush with no SD card
Yep, I did that last night. Trundled off into the bush about 15 minutes walk away from the car, all excited because there were a buttload of glowshrooms to see. We get to our first stop, set up our spots and pull cameras out. [-E-] The symbol of nightmares. The symbol that tells you there's no card in the (TWO!!!!) card slots that I have in my camera. I know that there are at least 10 cards in a case that I've definitely left in my car. I'm scrambling wildly for ANYTHING I can find in my camera bag, but it's futile. The cards are all a good hike away and my friend is happily shooting away because he brought everything he needed out (but unfortunately no spares, he totally would have helped me out if he did.)
Not one to shy away from an ***OPPORTUNITY*** (lol) I decided to work with what I had, and whipped out my new phone.
Because I'm the sharing kind, and not a gatekeeping asshole, the app that I used is called "Expert Raw" and it allows full control over absolutely everything. I could even manually focus. This app is about to become a part of my photography standard kit, because it's so convenient, and so fucking good.
Let's take a look at an image from last night's adventure. This is the original file as captured, with the exif data below it.

As you can see, this thing gives even high end DSLRs a (relative) run for their money. Every setting is completely customisable, with full control over absolutely every element.
My next hurdle was "ok, I'm out with just my phone and a full camera tripod, what am I going to do about stabilisation?" The answer was fairly simple. Just find a way to rest my phone against the tripod to hold it still. I'll be investing in a phone holder and mounting it with a standard bracket plate to keep in my camera bag 100% now, it would have made things a lot easier. I muddled through it and dropped my phone in the dirt a few times, but managed to figure out a "rest it on 2 of the legs, with the phone propped against the ball head mount" situation, and the rest is history.
From there, after I'd captured my raw images, it was time to give them a run in photoshop, there they behaved exactly like any other raw file from a camera. I was able to 1-click mask the background to tone down the green overtone that everything had, I could mess with my exposure, shadows and hue/tone/saturation sliders, and the result is this:

I think that pretty much speaks for itself. It was a timely lesson to become the student, even on the fly, even when you think you're all set for knowledge. Sometimes something will go wrong, and there are cool ways to get around it and still have a good time.
It's also a timely reminder that your gear isn't the thing that truly matters. Education is your greatest asset as a photographer, and if you really truly understand the principles of photography, you can achieve awesomeness with any bit of gear.