Fictional universes and crossovers have been around long before the Marvel Cinematic Universe. The Green Hornet radio show had a crossover with the Lone Ranger that kicked off the trend. In comics, the Marvel Universe started long before Stan Lee was at the helm.
But these crossovers have a problem: They can privilege business relationships ahead of storytelling immersion and really interesting universes. As the Tommy Westphall Universe shows, crossovers often become a map of business decisions rather than of integrated fictional stories, and that leads to worse stories.
