That's sorta what MetaBrainz did - they offer their whole DB as a single tarball dump, much like what Wikipedia does. I downloaded it in the order of an hour; if I need a MusicBrainz lookup, I just do a local query.

For this strategy to work, people need to actually use the DB dumps instead of just defaulting to scraping. Unfortunately scraping is trivially easy, particularly now that AI code assistants can write a working scraper in ~5-10 minutes.