Sure. But at the same time, if you make it a policy to forbid nailguns at the workplace, you have less people shooting themselves in the foot while you're not looking.
Anyway, this analogy isn't helping anyone. You think libs in source control is a problem because some people might not do it properly. I'm contending that there's nothing wrong with libs in source control--there's something wrong with letting people who might not do it properly near your source control.
There are clear benefits from having a package manager (if anything, pesky things like version numbers, direct dependencies, etc are self-documented). In addition, it does prevent people from taking shortcuts, and even good people take shortcuts when the deadline is short enough.
Anyway, this analogy isn't helping anyone. You think libs in source control is a problem because some people might not do it properly. I'm contending that there's nothing wrong with libs in source control--there's something wrong with letting people who might not do it properly near your source control.