Maybe yall remember when I was writing some conference proceedings last month. I finished them at the last minute (like everything else I do) and mailed in the LaTeX source, the original figures in eps and the resultant dvi/ps/pdf, just like the webpage said. I saw something about instructions for a photograph-ready hardcopy, and assumed it was a courtesy for participants who work in caves* and code on pre-RISC DECs with orange-on-black CRTs. I just got an email from the secretary who is gathering the contributions for the publisher. Everyone has to send in hardcopies. Like, mail in paper. Like, tree-paper. Like, physically. Like, with a stamp. …? I could see it if you submit via Word or some other format that intentionally discourages interoperability, but I used their LaTeX format with no additional (ie modern) packages.
This wasn’t my first rodeo, and I ain’t never had to do this before. I asked an olderwiser about it, and they said “Sometimes they ask you for it. Don’t.” I mean, I will do it, but man, that’s silly.
*no offense to folks at neutrino/DM experiments. Those are mines, not caves.
Imaginary Potential 
I worked for a while in the production department of a large science publisher, one that did also did lot of physics proceedings.
Though not related to the issue you point out here, a lot of the big publishers take submitted journal manuscripts and send them to India for manual editing and typesetting into the journal style, so when a journal asks for a specific format, most of the time they ignore your submission format and have the article re-typeset again.
If you spend a lot of time re-arranging article submissions, it might save you some time to check with the editor first whether this is really needed.
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