Relying on EXIF is a good thing. But if you limit yourself to ONLY using EXIF, you can't group images, make one image in a group the primary image, assign common metadata to the entire group, etc.

All turned out to be essential in my photo archives, especially as I started scanning old pictures. You get the front and back side of a photo, or you scan a large-format drawing in 16 scans and store them alongside the merged one, etc.

Aperture used to handle it pretty well, but Apple dropped it. I learned my lesson, and now I'll be doing things differently.