matroska is actually possibly cursed when you read the specs.
most of this stuff is unused in practice. it has like an entire hierarchical chapter system as well as a layered tagging system. its entirely legal to store an entire record or CD in a single MKA file, chaptered to each section of a song, and have them tagged like "ah yes that is the B2 part of this song's ABBA song structure
"
does anyone ever do this? lmao no they use cue files. which i promptly delete and reencode to flac/opus files.
you can also basically jam the whole damn nfo file in to those tags, or literally via attachments, to the point where its actually legal (and possibly useful) matroska to just slap all the episode data in to each file and not have those weird nfos and shit lying around.
i think MP4 inertia is because big tech pushes it hard, so media players support it, which leads to being able to download and drop it on an iphone or some set top box share and it works.
matroska is like opus in that all the decent stuff does support it just fine. it's just not the lowest common denominator.