The
guts of a J! website lie in articles. Although there are other extensions that people can use to display information (e.g. photo galleries, discussion forums, shopping carts/product listings, etc.), the J! CMS (and the development effort that goes into it) is focused on J! articles.
You can supplement those things with modules; you can tailor your web content with plugins and you can change the way that you display all of these things with templates. At the heart of J! is the article management (although there are other features, e.g. user management, media management, managing extensions, language features, etc., etc., etc.)
Way back in the days when we had J! 1.5 we didn't have version management for articles. If you edited/updated an article (and you "blew it") then you had to retrieve a previous version of that article from "somewhere". Along the way came version management for articles—some people use it and some people don't—which adds a little bit of overhead in terms of storage and processing. It's a useful feature; I've counted myself fortunate that I've dug myself out of holes of my own making by calling up an old version of an article and putting things back into order.
I agree with @waarnemer: if you use a module (or modules) that involve higher levels of "intelligence" beyond the vanilla-flavoured "custom module", then it's best to write your own installable module and maintain the different versions of that module on your PC. That way, if you blow something up, you can re-install the previous version of the module and you're back in business.
I don't spend a lot of time customising-to-the-
nth-degree "custom modules". If I use a custom module with a lot of extra "intelligence"—to quote @waarnemer—I develop it off-site or away from my production website(s) and, yes, I frequently backup my websites so I'm not likely to fall into the trap of shooting myself in the
derrière.
Interesting idea—to add version control to custom modules—but about as likely to get off the ground as a pigeon carrying a pallet of bricks on its back. Best wishes getting your idea to fly.
