An example that comes to mind.

Say you're 1-0 down with 5 minutes left. In points for a win, going for the equaliser and earning a point far outweighs conceding a second and still being on 0 so it's worth it.

But with only goal difference, going from -1 to 0 is the same as going from -1 to -2. It's equally good/bad. There's not more to gain for trying to equalise than trying to not make your result worse.