[jowiar]

2 theories:

(1) Node sprung up at the exact same time that NoSQL was in it's "fad" phase (which had much to do with fighting the now-mostly-solved scaling challenges of the SQL databases of the time). Both caught on with people who liked trying the hot new thing in 2010.

(2) There's definitely a bit more impedance mismatch when you're working with a SQL database from JS. If what you're trying to do is persist a blob of JSON, a NoSQL object/document store works at that level, whereas a SQL database requires thought and planning.

This is not to say that I prefer NoSQL, or that these are reasons why someone starting something now should choose NoSQL, but they do jump out to me as why backend JS dev has been a bit more NoSQL-happy over the years.