The thing is, sitting and kicking works. A front-runner will win when he (or she) is clearly the class of the field, but all else being equal, the sitter-and-kicker will beat a front-runner. It’s just easier to let someone else set the pace, and then use the energy you’ve saved to storm past at the end for the win.
I’m a firm believer in the Law of Natural Selection of Strategies, as promulgated by baseball writer Bill James: “If a [runner] tries something and wins, other [runners] will follow; if a [runner] tries something and loses, nobody else imitates it.” For as long humans have been racing, runners have been sitting and kicking – and winning.
Here’s an example from 1936:
If I were fast enough to make winning an option, I’d sit and kick too.