Some of these are debatable.

> Don't store your vendor directory in Git! Completely unnecessary and waste of 47MB.

While 47MB is indeed a bit large, storing vendor libraries alongside your code makes sure you have a working version when you pull down the repo. Nothing more frustrating than hunting down why the code you just checked out doesn't work.

> Don't commit your asset directories (they should be symlinks).

That depends on what you mean by assets. If there are binary assets needed for the app to run, they must be included. Imagine downloading a web app with all the icons and textures missing. Not good. And if source files exist for these assets, they should be in the repo, too (like PSDs or Inkscape SVGs)