I agree, this may cause more harm than good. Unless there’s a specific configuration of the theoretical auto-updater, people are going to end up having their edited script and/or config files overwritten. Perhaps something like a .gitignore file and an overwrite prompt? I don’t know.
So… This sounds like the basic concept Steam Workshop. There’s a wee bit difference though.
Stuff like vehicles/objects/peds/map mods don’t really require any changes to the files provided. Well. What if someone wants to edit them? If they’re not encrypted by the keymaster, one could just edit them and copy them over to a different resource (but that defeats the purpose of having an auto-updater in my opinion). No biggie.
The difference is with scripts/code. As far as I know the main idea behind the keymaster is to allow people to sell stuff on Tebex and not have it available to download for free on some third party website in a matter of minutes. So the solution was an encryption system. Steam Workshop on the other hand? No way to sell/purchase assets - No need to encrypt them.
So, asset creators can selectively choose which files are not encrypted (to allow for config files to be stored as .lua files for example or even just opt to not encrypt any files at all). Since people can edit these files, they most likely will. And what’s going to happen when there’s an auto-updater with no overwrite prompts and such? Their stuff is going to get overwritten. Custom NUI assets (js/css/html), any configs stored in the resource directory or just simply code edits - gone. Imagine the chaos from confused 
server owners in “FiveM Client Support” category 
.
There’s also some other things that would have to be taken into account. For example: Currently - asset creators can put multiple resource folders into a single .zip file. Let’s say a server owner only wants one of the resources from the .zip file. What happens then? I would personally really dislike the idea of having to put EVERY SINGLE RESOURCE FOLDER into a separate asset on keymaster as this would force me to maintain 100+ assets instead of about 20. Not to mention the (currently) utterly tedious process of updating multiple assets to the keymaster at once and (currently) literally no reliable method to automate it/integrate with CI/CD (like GitHub Actions for example). As mentioned here earlier this year:
Perhaps a solution to the auto-updater overwriting files would be to integrate it with txAdmin? What do you think about that? You open the panel, go to the resources tab, see all of the resources available, currently installed version, latest version and release dates. A button to manually update only a selected resource from list. Prompt with a changelog. Perhaps a on panel login prompt could be displayed? “Hey, since last time you logged in to the panel, these resources have been updated: foo, bar, baz. Would you like to update all of them - View changelogs/Yes/No”.
Not sure if there’s a better thread existing for this but I’m just trying to do some brainstorming here.