You can also do that with browserify you can split up your files such as vendor-bundle and app (for all of the user js) or you can go further and split per page, module, etc and server it up via xhr, server, etc
So i guess i still dont see how webpack is worth all of that ;)
Ok, maybe its just me knowing browserify not well enough, but maybe its that there are not enough articles that promote advanced features. Even the docs don't tell about this. The only bit I can find is in one of the last sentences of the handbook (and only cause you mentioned that this feature exists). So we are back to your initial point about the reading tons of docs ;)
Btw. for me the feature of having multiple entry points is essential for a package manager on client side.