This is a wildly incorrect approach. Ideally, they would separate the core of what's necessary for any one thing into one composer package, and then everything else into their own (e.g. a youtube package, a drive package, etc.)

This way.. I can see you having a code dependency that needs Drive, but b/c you've cleaned out everything except YouTube it's going to fail - and that's sort of breaking the way Composer is supposed to work.