For those who are able to stomach an uncomfortable political history instead of an easy, technical answer, you can take a look at [2]. It's interesting that 7 years later, many the folks who pushed hard to get rid of SQL in favor of NoSQL seem to no longer occupy positions of prominence in the industry.
[1] https://developer.mozilla.org/en-US/docs/Web/API/IndexedDB_A...
[2] https://nolanlawson.com/2014/04/26/web-sql-database-in-memor...