But that won’t work if I have duplicate titles!
Like the doctor said: so don’t do that. Challenge yourself to create brief, unique, effective titles. I have over 1,100 posts on this site, and there aren’t any duplicate titles.
(While you’re at it, shorten your titles, too. Make every word earn its place. You’re going for a timeless, headline-like quality - not the waffly, run-on title of a scientific paper.)
It really depends on each blog, Matt writes a personal blog so of course with a bit of diligence is possible for him to have unique links after decades, but that's not for everybody. And a '-2' in the url is terribly ugly, even more than having a date. My stance is, if you're sure that you are going to have unique titles than sure, what Matt says is golden. If not, I'd think twice before doing it. Remember that if you want you can start by only keeping the year and forcing yourself to have a unique title for each entry every single year.
Update 2019: I finally followed Matt advice and I like it. URLs are shorter and to the point. It is sometimes harder to find the right title if you like to write about similar topics often, but it's surely doable. It's especially good if your content is evergreen and doesn't follow a news cycle that is only relevant for a few days or week. In the latter I'd say the date is useful and should be kept. Since most blogs though don't tend to follow the news cycle you should go ahead and drop it. Try it for a year and you'll see if it's right for you.