You can absolutely winterize a house. My dad did it in Maine for a number of years when he was leaving the house for the winter. But as I recall it was something of an operation to both winterize it and dewinterize it--which he called a plumber in for.
One of the problems with winter power outages is that even if you're prepared to winterize everything by yourself, you probably don't know that it's going to be an extended outage (which is generally rare) so it doesn't make sense to immediately take drastic steps.
