I'm curious as to where/how exactly MyAnimeList gets their data. I understand there are a lot of similar services that let you "Manage watching anime", and I found them to mostly scraping the data they use from MAL (Or previously the MAL API).
AniDB and AniList were some of the larger players I found.
AniDB provides a reference to where the data (I assume) comes from:
So for a random anime I inspected, I was able to see that AniDB has used Wikipedia, MAL, as well as a few Japanese sites.
As for AniList and MAL, I could not find anything relevant.
So, where was/is the root of all the data? Did these services originally scrape from somewhere?