The real "complexity" that matters, as someone who has used most modern static site generators and front-end js frameworks, is in not knowing how or what broke, and how to fix it, when inevitably something breaks. E.g: with jekyll if you develop or modify content on a windows box, test locally, and then push to GH Pages, but Pages builds the site using unix, and some ruby gem or jekyll plugin doesn't work consistently across them, and it takes a good bit of experience and googling around the errors to find a fix or a workaround.
If you essentially made your own static site generator, at least you would know what went wrong and come up with the straightest line to the resolution (even if that's just modifying the build output by hand in an extreme case).