It's much easier to ship more than one program, with all their dependencies packaged, because of lower cost of maintenance per program/library. It is also easier to automate downloading and unpacking than do that manually for every package. If you want to try this idea, just download a Linux distribution.
Doesn't that fail the minute one of your programs decides he needs a different package version or one that doesn't exist all together?
It looks more efficient and easier at first, but ultimately it becomes less and less maintenable and the "dumb" inefficient approach of shipping all the things at once becomes better.
It's like in real life, the more you are dependent on different peoples/incomes, the more your life becomes complicated and unlivable. Just ask someone who needs multiple jobs to survive. But we went ahead and implemented just that into software. Kinda madness...
