It's more complicated than just "Does Quibi own the content"- Quibi struck deals with content creators for the creators to create the content and own it, but to give Quibi an exclusive license to the content for 2 years. So whilst it's technically true that the content creators still own the content, the vast majority of the value is in the rights to that content. They justified this as some creator friendly move, but frankly I think they knew that by 2 years time Quibi was either huge or dead.
Well most of the content is crap anyway, but right now there's a lack of content due to Amazon/Netflix/Apple etc. bidding up the market and covid limiting supply. So 1.5years of exclusive is probabbly 90% of the value of the content, and if it's still valuable afterwards you can license it from the original creators. Stuff drops off Netflix all the time.