Yup, lotta myths about tire's going bad like the tomatos in your fridge. Of course, most folks couldn't find a born on date on a tire if you held a gun to their head.
I usta buy mostly used tires for our vehicles (better value than new from the tire shop, kinda like a new car vs used). Anymore, the value in that market seems to not be there, at least in this area (based on highly scientific Craigslist tire shopping, lol).
But with that, knowing that something your were buying wasn't already 5 years old even though it looked new was important.
If you go to the tire shop and get new tires off the rack and bitsch if they're 6-12 months old, something is a little off with you upstairs!