RealGM

For example points scored in playoffs, they don't count in your career stats.

This way everyone can be compared under similar circumstances in the regular season. You wouldn't want to make the data un-comparable because you have different conditions and opportunities for each player. Everyone has the chance to play the regular season, not everyone has a chance to play the same number of playoff rounds each year. The playoff data is still there, it is just separated off so you can compare apples to apples.

OP, I really think you know the exact answer to this. This is pretty self explanatory but Luigi nailed it down for you.