Because snow happens for extended amounts of time every year in relevant regions which are huge, whereas huge earthquakes happen only at faultline regions and only once a century or so.
Also, "severing pipelines" on regional level doesn't really matter in case of earthquake for single household in case we're discussing. If you get severed connections from disaster, chances are that you either leave the region if roads are still operable and logistics work until basic damage control has been done by emergency services, or they are too damaged to allow you to leave and you're stuck and limited to what you have directly on site.
In which case, you likely have far more energy in a single tank of your ICE generator than in a battery bank.