That may be the most idiotic and worst tire advice I have ever read.I think what you need to consider is this: Do you want to spend money on winter tires for normal winter driving + snow chains for those freak times of massive accumulation of snow (Do not drive with chains on pavement!), or do you want to buy an AWD/4WD vehicle + winter tires. Either way you are going to need to buy winter tires to drive in any temp below 40F.
Below 40F all-season tires start to become hard, like a chocolate bar in your fridge, and because of that they loose traction. Winter tires stay soft at much lower temperatures. So even if you never go near a snowflake, if you really want traction in freezing temperatures, winter tires are the way to go. In your case you're going up a mountain in the winter, best traction in ice/snow/slush is winter tires.
I live in New England where it (shockingly) gets below 40F quite often. It even snows! I have never owned an AWD car or snow tires. Often times, M+S all-season tires will be good enough to get you where you need to go. There were a few storms this year I didn't attempt to drive in due to not having snow tires, so this season I think I will get snow tires if I wind up still having my current Ford Fusion (FWD). With snow tires, it should be plenty good enough in almost anything... unless the snow is too high where ground clearance becomes an issue. And when that happens, the state usually issues a "State of Emergency" where legally you are not to be out on the roads.
Next car we're looking at will most likely be an AWD/4WD SUV and might just go ahead and get a set of snow tires for winter. At that point, it'll handle just about anything New England has to offer weather-wise.
We don't get the storms like some of you guys out West and don't have chain laws at all. When we were out in Colorado and saw those signs for the first time, it was quite interesting!
I will say, if I lived out West, I'd have an AWD/4WD SUV or truck with snow tires for the winters... because why not?