The "They’re enough" is ofcourse a little silly. Yes there are thousands of combinations if your short url contains any character. But his example is about words and that will leave you with less combinations.
Exactly. Unless your blog is incredibly broad, you're probably writing about the same subject more than once. What is the author going to do when they write about short urls next time? /su2?
I think I'd prefer it if you were creative with the content of your posts rather than your urls :) I mean, if you think there's no value in the content of the url whatsoever, then just start at /1 and work upwards...
But I like the essence of the post.