Interlaced video files should no longer exist.
Seriously, fk interlaced video.
> upscaling algorithms can invent information that doesn’t exist in the image
That's not a falsehood. Upscaling does invent information that doesn't exist in the image.
Yes, they should, as should silent movies, black and white movies, old game consoles with exotic output formats like vector graphics, and the like.
It is a worthy endeavor to create and maintain video playback software that lets people consume beloved content that was made to the technology of its day, including home videos, sports games, TV shows with special effects edited in 60i, and video games.
The upscaled image does not have more information than what was in the original image; you can reconstruct the upscaled image given only the information available in the original image, the output resolution dimensions, and upscaling algorithm.