According to interviews, Kevin Burke and Chris Wyatt wanted to tell stories longer than twenty minutes. I'm not trying to defend the airing or format of the episodes, but those fade-outs that lead to the Part 2 of the episodes were probably a precaution in case Disney XD decided to rerun the show and split the parts up. That's what Avatar the Last Airbender did with their hour-long episodes after their aired in reruns.
Here's an interview with Kevin Burke and Chris Wyatt, along with Venom and Ms. Marvel's actors, at D3 2019.