The points help abstract away the task estimates from actual time worked. If you estimate that you will do 40 hours of tasks and only complete 30 "hours" of ta

The points help abstract away the task estimates from actual time worked. If you estimate that you will do 40 hours of tasks and only complete 30 "hours" of tasks because one of them turns out to be more complicated than estimated, it's hard to explain that to most people. It's easier to say you did 30/40 points because <task> was more work than anticipated. The separation of points and hours worked also helps a little bit with some perception issues when comparing developers, as human emotions tend to get involved if people feel accused of being inefficient or working less. But you are right that it does not have to be more complicated than estimating hours.