Why are there no card points in a null contract in skat?

In a null contract in skat, there are no card points because the objective of the game changes entirely. While the goal in standard trump or grand contracts is to capture a specific number of card points (such as 61, 91, or all tricks) to win, the sole objective in a null contract is for the declarer to lose every single trick.1

Because the game is defined by the requirement to avoid taking any tricks, the traditional point values assigned to cards are irrelevant to the outcome. Consequently, null bids are played without trumps or card points, and the game relies solely on the rank of the cards to determine if the declarer successfully avoids winning a trick.1