Why not? I mean, you could ask the same question for 1 week, 1 month, 6 months, whatever.
And I don't think it's an immediate zero-to-normal kind of situation. You might be unable to get much/any food at all for a week or three, and then you might only be able to get emergency rations from the government. And then after a few months, some staples might start trickling in, with increasing quantities over time.
Eventually, after a year or so, things might be back to some reasonable percentage of normal. But all throughout, given high levels of stress, anxiety, and uncertainty, it'd probably be nice to not have to worry too much about what kind and quantity of food you'll be able to get, because you already have enough to last you a long time.
If we're talking about "a couple" years, and the situation is still essentially that no food is available for purchase or from the government, I expect the situation is so bad that society has at least partially collapsed. By that point I would think you would have needed to relocate, and have started growing your own food or hunting, well before you get to the couple-of-years point. But I suppose if you did actually store a couple of years of food, and you had a stable, safe, and secure shelter location, you could probably stay.
> Why not? I mean, you could ask the same question for 1 week, 1 month, 6 months, whatever.
Of course, that's why I'm asking! For some time periods there are some pretty obvious answers. A fairly routine natural disaster like a flood or blizzard could easily disrupt food access for a week. A month is probably more difficult to imagine, at least in very wealthy nations/regions. At 6 months I think it already starts to get difficult to imagine the scenario.