Funny, but on thi forum alone, every person who's tried to install the proprietary nvidia drivers on ubuntu/Mint has ran into the missing GUI and needing workarounds issue. I've seen it on several computers, all in fact. So I kinda doubt it "works for most" people. I'd say most people never install the proprietary drivers, or they do the horrible workarounds to make them work.
I haven't looked at all those threads, but at least a few of the cases I saw were PEBKAC lol (trying to install the .run file from nvidia/ati instead of using the more reliable solution of using the included automated installer). My old laptop had an AMD card and I was always able to enable it via ubuntu's driver installer. I do agree that the proprietary drivers definitely aren't perfect and tend to be more problematic than the OSS drivers (I chose to go intel on my current laptop so I wouldn't have to deal with them), but I wouldn't say that they just don't work at all for most people based on some forum posts.