That's odd... but hey, apparently there are still people using it for... compatibility purposes?
I don't know...
Besides, I thought MPEG-2 was far more common than Xvid, not just for DVDs that are still being produced for some odd reason, but also for all the SD 480i or 576i TV channels out there that are still on air and also HD/FULL HD standards like XDCAM which just don't wanna die...
It feels weird to talk about these things in 2021, but hey, they're still a thing...