m4a to MP3 conversion

[EEPhil]

In a post on the youtube-dl thread BH quoted the command he used for audio conversion:

ffmpeg -i radio_show.m4a -c:v copy -c:a libmp3lame -q:a 4 radio-show.mp3

I, not for the first time, misread the contribution and thought the quoted command failed. It doesn't. But it looks odd to me - copying a video stream in an audio to audio conversion. I tried it, it works. I also typed "ffmpeg m4a to MP3 conversion" into DuckDuckGo. The AI slop gave the same command as above (bar the file prefix), which in turn was quoted in one of the URLs listed by the search.
Surely the -c:v copyis redundant. Wouldn't you use-vn if you need to make sure there is no video? Can you even have a video stream in an MP3 file?