I think the same is probably true for VLC to a lesser extent, which is pretty wild considering I've never heard of it being used as an attack vector, e.g. via torrents.
> I doubt it'd be worth one's time to write exploits for desktop Linux
How many developers, network administrators, etc. run desktop Linux? Gaining access to those can be very, very valuable.
It's worth pointing out that many, many, many things use the libav* library family.
If the exploit chain involves the user downloading and opening a file, something like >99% of the time the next step already involves executable code (or Office macros), which makes any ffmpeg vuln completely useless.
Budget web host using outdated software getting hacked because they havent updated in 2 years isn't exactly all that interesting of a blog post even if the victim knows enough to figure out what happened.