> since you can't tell what should be removed, or more importantly, what can be removed

Isn't that what dependency detection does? Whenever I'm not sure if something can be removed, I just try to remove it, and if it would break something else, the package manager tells me. I can broaden my scope and see if that's also an unnecessary dependency for something and follow the chain, with it eventually ending up with a set of packages where I actually get the prompt to proceed or not (meaning nothing in it is a required dependency for anything remaining), or I see a package I definitely want to keep around and stop. If I'm interested in what's part of the base system, I just check the metapackage for the base system.

This doesn't sound like something that's a problem with package managers in general compared to maybe some distros just using them poorly.