Copy+paste from the github repos of each package is hardly superior to just having package management. Node doesn't magically make every program bulky. Avoid authors that feel the need to include lots of bulky packages.

Copy and paste makes the developer aware of how much they are dragging in. Its easy to run yarn add and then import millions of lines of code. If you tried to do that by hand you would stop and rethink if isOdd() actually requires that much code.

even if you just do copy+paste you copy over less dependencies because there is a cost. Each time you wonder: is it worth it? Ideally you don't do it at all though. As for avoiding authors who bloat up your hard disk, it's easier done on a platform that puts stones into their way like GNME does.