TBH, I don't buy the QC argument, people (as stated before) will just use a flatbed scanner to scan a print, remove the logo from the print and do what they want. Perhaps the photographer should also keep the prints in a locked safe to prevent them being scanned?
The only real advantage I can see in user-removed's argument, is that he can offer a low headline price? My two kids are little shits when posing for photographs, I'd feel bad if a photographer gives up 3 hours to do a shoot for £60 and I don't order any prints through no fault of the photographers. Equally, some of the prices for prints seem excessive, so if I did want more prints, I'd order minimal quantities, and scan them, because I ain't gonna pay £20 for a 7×5.
Why would you want to wrest control from those that know what they're doing anyway?!
Because photographers move on, take other careers, go under… I want to keep the digital negatives of pic's of my kids when they were young until I die…and then pass them on. I can't believe I will be alone in wanting to do that?