Also No-SQL is Document Based .... IMAGINE like your character info and everything is stored in document in JSON format would be nice. You can add or remove as you see needed. But that comes at a cost (performance and potentially bug prone if not handled correctly.) Honestly it would be more beneficial to use in MMO's, but not completely. Having to join tables over and over. If its not cached just takes too much time. Also caching takes too much memory. Alot of companies go the route of SQL, which is relational which is fine for the most part... but i don't think all my character data should be stored across multiple tables that seems costly as hell to query, and takes up precious computing time on the servers. I would actually use No-SQL for certain parts of the MMO backend and SQL for other parts (say the data analytics they gather.). I don't know why tbh they don't having to deal with all the joins and stuff is annoying programming, and im almost certain things could be made alot faster if programmers made NoSQL and SQL work together.

Like for example assuming that character data is all relational and items etc.
You have to join the character table on the items table. (Again performance cost.)
Now however that is assuming their is one table for items, and 1 for character. but say they have 10 columns or whatever.. for the individual items they have. They could just pull it from one table. Which would be alright. But if its seperated into rows, oh buddy...

In a NOSQL - SQL hybrid you could be like CharacterItemsEquipped = 1,2,3,4,5,6,7,8,9 (being item indexes) do an SQL QUery where ItemIndex = CharacterItemsEquipped and return the items pretty fast, then it simpler to just update the table of items when a stat squish is needed.