>>52992101because she is the endgame for Ash, that's why. the way they paired Ash and Dawn together and Goh and Chloe should be obvious, she got the most shipping moments with Ash and SHE was chosen to be at the finals for Ash. not only that, Chloe was almost completely uninterested in Ash's battle only being there to show Eevee a battle. At the same time Dawn, on the other hand, was completely immersed in Ash's battle giving it her all cheering for him.
not only that, they really did make everyone else look like bad friends when she was the only one to show up. let me say that again, THE WRITERS made all the other companions look like assholes in favor of Dawn I mean what you said is true multiple other characters were available to be there in person but yet the writers left them out.
Dawn showing up out of nowhere makes complete sense because that's who they ship, it's Ash x Dawn