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Why Static Site Generators Are The Next Big Thing: https://www.smashingmagazine.com/2015/11/modern-static-website-generators-next-big-thing/
Someone got it 3 years ago.
One of the shortcomings of HTML websites that the LAMP stack promised to solve (& did at a price) is the absence of theming/templating. But the W3C actually solved that long ago in a powerful way: XML + XSLT. An XSLT file can turn XML data into HTML pages very easily & quickly, but LAMP's pains were so much easier to live with that XSLT never got far enough beyond browser support to have CLI tools.
I'm going a bit more old-school with mine (favoring POSIX compliance over New Shinies for the most part), but the article is right about the main motivation & timing reasons: dynamic websites are slow, buggy, & often overkill; & LMLs are mature.