This problem was also an issue for movies and theaters. The "fix" is to ensure theaters (the distributors) cannot be owned by, nor can they own production studios.
So under this rule, if disney wanted to have their own streaming service and used a high licensing fee to try stop competitors from their content, they'd pay high taxes due to the high licensing fees making huge (fake) profits for the parent company - it'd end in losses, as the streaming service (as a separate company) cannot bill their cost onto the parent company (to offset the profit). It's as if the tax man gets to sit in the middle, and siphon part of that license fee for free. Disney shareholders would never stand for that, and so they won't do it.
So under this rule, if disney wanted to have their own streaming service and used a high licensing fee to try stop competitors from their content, they'd pay high taxes due to the high licensing fees making huge (fake) profits for the parent company - it'd end in losses, as the streaming service (as a separate company) cannot bill their cost onto the parent company (to offset the profit). It's as if the tax man gets to sit in the middle, and siphon part of that license fee for free. Disney shareholders would never stand for that, and so they won't do it.