Year on Bottle
Most whiskies do not label the year they were put into the barrel. They only put the number of years it was in the barrel. This is because, like your example, Balvenie Doublewood 12 is released often year after year. It's probably also been put into barrels year after year, so they are barreling the same raw spirit each year and aging it 12 years. Same for Laphroaig 10. They make what will become "Laphroaig 10" every day (I'm guessing) and barrel it up and label the barrel. 10 years later the spirit is bottled and labeled a 10 yo whisky.
I think the main reason for this labeling, as opposed to vintage labeling like wines, is that whisky does not age at all once it's bottled. So, a Laphroaig 10 bottled in 1990 won't be all that different than a Laphroaig 10 bottled in 2001, if at all. So, vintage isn't important when you're talking about the age of whisky.
Now, some distilleries to put vintage statements on their whiskies, sometimes, too. Glenrothes, among others does this. This leads to my question, which is, what is the point of vintage labeling in whisky?