I don't want to need to have a centralized account to access my media library on my device.
I don't want to have to pay monthly to enable hardware transcoding.
There are very specific and common standard on renaming video files to contain "metadata" so that every single tool doesn't have to use ffmpeg to investigate and try to guess the exact movie/tv show from the title.
The Plex naming guidelines are pretty good: https://support.plex.tv/articles/naming-and-organizing-your-...
Some people like to add resolution and audio track information to the file name too.