That used to work everywhere, including Linux, where I want to do the backup, but now it requires iTunes, which I have no other use for and limits the entire process to 2 OSes.
The DCIM folder isn't really standard either, there's magic that happens when you start a transfer to convert the Harry Potter photos to standard photos and, I think, video to mp4. If the device doesn't have enough free space to do those conversions, there is no error message on the PC or device, it just stops mid-transfer (1 hour of my day figuring that one out). There's a setting to not do that conversion, but then you end up backing up files you can't read just anywhere. If it were just my phone, I'd turn off those formats on the phone, but it's my entire families devices.