You should be filming for your subject and media devices should be built around common filming aspect ratios. A phone camera's aspect ratio should be practical for capturing typical content, a phone screen's aspect ratio should mirror phone cameras, I think this is already approximately the case. Phones are somewhat unique compared to say a TV because they can easily be viewed vertical and horizontal, so really they have two aspect ratios.

I think the vertical photo and video phenomenon is more a symptom of how we use our devices. People are rapid fire swiping through media which means the majority aspect ratio is going to push the minority one out, which is why landscape is dead. Another reason I believe is people switching between apps, Tiktoking at the same time they use other social media for example, and often those apps are way more practical in portrait.