A lot of the DCF standard is designed around the limitations of FAT file systems, e.g. filenames limited to 8+3 characters, directories limited to 9999 "items" (which I assume is to make sure that there won't be more than 65,536 files in a directory). As Pixel phones don't use FAT, Google probably doesn't feel bound by this standard. Their naming convention allows the phones to store all photos/videos in a single directory.