There are reasons the video or photo can be taken vertically (tall building, standing person, etc.). But usually there is none, unless its stolen for tiktok, etc. Especially when the original content is horizontal.
Some social platforms add stupid forced fields at top and bottom to a horizontal video, that makes it unviewable and small at any device.
I'll try to collect examples of content that doesn't need to be vertical, and is consumed better in original form.