The general idea is that if your productivity relies on external plugins, it will drop very low as soon as you have to use someone else's machine, or when you have to work with lots of various systems where setting up your environment isn't an option.
I think it's more that everyone is taking the bus to Abilene. Can you explain the first point a bit more? On the second point, you can always :e scp if you need to.
I've never maintained my own .vimrc, or know what plugins I have installed or not, btw.
