There's only so much you can learn from EXIF anyway. Knowing shutter speed, aperture and ISO won't enable you to recreate someone's lighting for instance. The full metadata may contain some aspects of the post processing at the RAW stage, but anything done in Photoshop won't be logged. It won't explain if any filters (real filters) have been used. If the image is a composite, then you've no idea what part of the composite is providing the matadata. I've just taken some images for a local theatre production, and the shots of the actors were comped into a shot of a forest. The forest image was taken by me ages ago on a D2x, but the actual images of actors were on a D800E. After comping in Photoshop and saving out the final TIFF for print, the EXIF of that TIFF says it's taken on a D2X with a shutter speed of 3 seconds or something. So what would THAT have taught you?
Or as I've already said, it's removed because many professionals use the metadata to also log client details for cataloguing and there would be stuff like client phone number, address etc all in the IPTC... so if a job for a client gets posted online, it gets ALL metadata removed. So YES.. sometimes they ARE hiding stuff from you
It is though... you have no right to it, and you can't complain if it's not there.