What do you think is the good reason?

because writing HTML manually is fucking terrible compared to authoring markdown. We (i.e. everybody) are trying to improve things because they are bad.

I mean, I agree that incremental improvements are great but also I think your hyperbole is a bit of an overreaction. I use markdown and templates and Software people rightly prefer reuse and DRY principles but handwriting html is honestly only barely a notch more primitive.

HTML files can't reuse anything, HTML is a pretty bad verbose language, it is hard to keep indexes and links up to date when you change your site, and well, a lot of other reasons that I didn't think about because I gave-up on that in the 90's.

I'm not being sarcastic. It is what I've done for 20+ years (although I only switched from thttpd to nginx in ~2010). The linked article does not really teach you how to use hugo. It just shows how to generate a single page, and there are far better ways to do that.

And like others have said, nginx comes with server side includes built in. It's the perfect amount of dynamic templating power with the minimal attack surface. Before anyone jumps in with, "but I can deploy (or other cargo cult terms) my website to a CDN if I use Hugo for templating." I question the utility and complexity of bringing in a CDN in this, minimum viable context or any personal website context.

I can deploy [sic] my website to a static file serving service for virtually free (e.g. S3, GitHub Pages, Azure Static Sites, etc.) without having a CDN and without having to worry about renewing SSL certs, managing a full linux instance or container, patching the web server when stuff gets hacked, doing maintenance, etc.

There's a ton of value in 'just static pages', and if you do more than 1, not writing your own HTML is pretty great.