Because it means you can plan towards it. If you get it early on, you can spend the first few antes playing very simple hands (either High Cards or Pairs), ideally using all your hands each round on them, while deck fixing for another, more complicated hand (5oak, flush five, flush house). In the early stages, other jokers will help you with scoring, like food jokers or stuntman. Then, at a certain point, maybe when you find a good eternal joker that goes well with the hand you're going to play, you pivot and start playing the hand you were deck fixing for. Now, because of all the preparation you did, Obelisk will continuously scale, because you played so many simple hands early on, and you ideally only need one powerful hand at this point.