Trivia to one person, might be critical essential information to someone else. That Spank Hopkins played the drums on Israeli Geography 101 is also “trivia”.
One of the things MusicBrainz (and MusicBrainz identifiers) are in a good position of is functioning as a “rosetta stone” for music services, storing/keeping identifiers of any kind is essential for this function. (Whether Windows Store IDs are worth of keeping around or not, I don’t know.)