It strikes me: In the amount of time I’ve spent working around quirks in my current static site generator engine plus the amount of time I’ve spent waiting around for it because of its slow design and not-great data structure choices, I’m quite sure I could have written my own.
That isn’t to discredit the folks behind the tech I’m currently using (I didn’t name it apurpose!) so much as to affirm @brandur’s point many years ago:
I’ve found that assembling my own static site generation script takes about the same amount of time as getting on-boarded with any of the major site generation frameworks. This isn’t as much a critique of them as it is a nod to the inevitability of any general-purpose project to expand in features until it takes a lot of documentation and false starts to get up to speed. Writing your own script may be a greater maintenance burden over the long run, but this is offset by the much improved flexibility that it gets you.