Quick glance through ingredients shows:

Elmer's No-Wrinkle Rubber Cement
>70% Heptane
20-25% natural latex rubber
1-5% Isopropol alcohol

Rema Vulcanizing Fluid
60-95% Naphtha, petroleum, hydrotreated light
1-2.5% N-Ethylcyclohexylamine
other brands also contains: acetone, heptane, trichlorethylene, zinc-dibutyl dithiocarbamate/dibutylamine

Now we can see that the office-stationary "rubber cement" is clearly of different composition than "vulcanizing fluid" regardless of how it's labeled. Leave a bottle of rubber-cement open and you end up with a ball of rubber about 25% the size of the container. Leave a bottle of vulcanizing fluid open and it evaporates to nothing; very different stuff. The N-Ethylcyclohexylamine is a vulcanizing accelerator/catalyst which speeds up vulcanizing enough to occur at room-temperature (heat does the same thing). Ever see "RTV" on various rubber-sealants like caulk? The red uncured rubber on the patches provides the sulfur and in the old days with skinwall tyres, you can see a brown circle appearing on your tyre if you install the patched tube right away. This is caused by the release of various gases during the curing process.

A lot has changed in the past 20-30 years. Just because there was only one way to vulcanize rubber 30-years ago, doesn't mean that technology hasn't improved. Look at how materials technology has improved in frame materials, and how mechanical engineering designs created index shifting. Auto and computer technology has improved significantly in the past 30-years.

In the end, it's not an all-or-nothing, black & white, yes/no issue on patches. It comes down to a shades-of-grey on how well various compounds holds a patch to a tube. I'll do a demo video of "rubber cement" versus "vulcanizing fluid" after 24-hrs curing and show how easy or difficult it is to pull off a patch using both these products.