I just wonder that if they're not savvy enough to use a RCS what other types of battles will you have to fight in the future?

If I was in your shoes, I'd start looking for another job with a company with a bit more technical sophistication. Somewhere that the battles you fight aren't over trivial technology problems and practices and issues that already have solutions.

Now that doesn't solve your problem, so probably the best thing is start using an RCS yourself, then create a build system that will push changes out to the server. You could initially sell this as a time-saver in updating the server. Then start selling the whole history part of using an RCS to go back to previous versions of a file.

But, if they're not using an RCS in the 21st century, what else are they doing wrong, and should you really stay there? :)