I can give you, and anyone that said chromebook, a point but how many people do actually use tablets / mobile devices to do some actual developing? Everyone would love and we can already, just nobody does it because it's not comfortable and we all know that to write something decent you need to be comfortable.

On the anywhere part, it's a very similar situation, I feel like source control it's better because in the end you don't want your code to end up on any possible computer and you have more control of what you can do.