Because literally 2 weeks ago, I dropped my license while pulling a dog poop bag from my pocket while on a run with my dog. I did not realize I had lost it until I was home and undressing and went to pull the license out of my pocket. I immediately ordered one online (after going back to the park and diligently searching for it), but it still took 10 days to get to me. Which meant I was driving without any license or form of ID for 10 days. That's when I discovered my state has their own mobile ID app.
So yea, I would have felt much more comfortable had I had a digital copy of the license on my phone those 10 days.
And no, I haven't left AZ since the pandemic began, although I hope to do so next year. And yes, I will carry both the physical and the digital IDs with me. Accidents happen. I have been robbed before and was without a license and therefore ID for about the same 10 days when that happened, too, but that was back in the days of flip phones.
That is why I am eager to have both.