There are many reasons that Google Photos isn't my only backup destination. Most people know (or should know) that you shouldn't trust a single destination for the backup of data when the data is important. For me, probably my most important data is the memories preserved in the photos that I take. They are priceless.
I have literally been doing backups this way for years. Google Photos has never had a problem handling it until recently. I know an app can be confused when things like this happen. As an occasional developer myself, I know that often these kinds of things need to be taken care of in code. Obviously some software engineers understood this in the previous versions of Google Photos.
Another great reason why this kind of exception handling is important is a lot of people have configured their phones to store photos on their SD cards. If the user pulls the SD card from their phone do you want that to break Google Photos when a simple "if" statement could correct the issue? In bash scripting it would be as simple as:
if [ ! -f /sdcard/DCIM/Camera/photo.jpg ]; then pull from cloud; fi
Anyway, I don't mean to rant, and maybe this issue does not deserve any attention. I could easily file this with about a dozen of "things Google has broken and never fixed" kind of issues. I thought I might as well make the problem vocal and hope that a program that I have loved and used for years can continue to be my "go to" photo app.