Keep in mind the major factors in food storage are temperature, light, oxygen, moisture, and time. While metal canned products control oxygen, moisture, and light very well, the two variables are temperature and time. We can judge time based upon the BB date stamp, but temperature exposure over that time may be hard to see. The USDA states that generally a constant 10 degree cooler storage temperature doubles storage life, and conversely a 10 degree increase in constant storage temperature halves storage life.
So if canned goods are labeled 2 years (at 70 degree room temp) but are stored (or transported?) in an un-airconditioned warehouse for 90 days at 90 degrees, there could only be 90 days of shelf life left, in spite of the 21-month ahead date. Something to think about. Cans of food kept out in a backyard storage shed could be worthless after one summer if that shed gets 110-120 degrees in the sun.
As foods age, they not only loose flavor, but also nutritional value. Sure, a person might be able to eat a ten year old can of so-and-so with no I'll effects, but all they may be getting out of it is bulk, little actual food value. Even dried foods will loose food value over time. The best retainer of value is freeze dried, it can have nutritional values still in the 90 percentiles after 25 years, when constantly kept in cool temperatures.