Software development is still sales. To successfully roll out a new internal product you need to sell your colleagues on it. To overhaul an existing architecture you need to sell your manager on its necessity. To prevent your coworker from making what you feel to be a poor choice, you need to sell her on your point of view.
Agreed. There is a sense in which almost all meaningful and social tasks are "sales". Scare quotes are used there, not because the same skill sets don't apply, but because you typically aren't actually transacting over the results of the conversation.
