I agree with Steve.
The drinking window offers a starting point if you will, with an educated guess of life span.
You will often notice these windows will change when the wine is re-tasted again, many times at the wines 10th anniversary. You can only call it as you see it when you taste it.
I find a tasting note or drinking window of value within the first five years. Much after that it serves little purpose for me. I also find a rating of a wine 10,15 or 20 years ago of little use until tasted again.
While it is indeed a guess, some are far more educated than others, and I seek out opinions from palates I respect.