Whenever a new fighter is introduced in Super Smash Bros. Ultimate, they usually come alongside multiple other characters and locations from their franchise. In the case of Sora, the final DLC fighter, there's a notable exclusion that has some fans scratching their heads. Aside from Sora and other Kingdom Hearts original characters and locations, there are absolutely no Disney characters or locations to be found in the DLC. This has led some players to debate over the true cause, with most falling in to one of two camps. On the one hand, some feel as though it is Disney's protective attitude towards its properties that has hindered the collaboration, while others think it is Nintendo's decision to avoid the inclusion of non-video game characters.
For those that don't know, the creator of Super Smash Bros. and the director of Super Smash Bros. Ultimate, Masahiro Sakurai, has long held onto his conviction that only characters originally from video games can be in Smash. It's for this reason that characters like Goku have been shot down and considered unlikely. Though Sora fits into this category, his many Disney friends (including long-term companions Donald and Goofy) do not.
Likewise, Disney has always been very careful with its intellectual properties, making sure not to allow any of them to be misused in any way that might misrepresent the company's brand and values. This has resulted in Disney becoming somewhat infamous in this regard, and is the primary reason fans thought Sora in Smash Ultimate would be impossible. Now that he's here, it's become the main talking point of why there are no Disney characters in the collaboration.
The Reddit post above sums up the situation quite nicely (and with a The Road to El Dorado reference at that). While it's impossible to say with any degree of certainty which of the two reasons is primary, it's highly likely that both played a factor in the decision. Disney likely found it easier to just send over Sora and some Kingdom Hearts specific characters and locations, and Sakurai and Nintendo probably didn't want the non-video game characters anyway.
With that in mind, this discussion between Nintendo and Disney likely went off without a hitch, even if others required quite a bit of legwork on behalf of Sakurai to get done. Whatever the reason may be, players should just appreciate that such a major collaboration was possible in the first place.
Super Smash Bros. Ultimate is available now on Nintendo Switch.