Free alternative: Host WP yourself? Use a different static site generator?
Come on, this clearly isn't yet-another-static-site generator for hackers but a commercial product for people who still use Wordpress, but not so foolish/desperate/cheap that they don't realise the security implications.
There are a couple of free plugins to make WP sites static, using various methods. So yes, use a plugin and you can get an HTML copy of your WP site with caveats that should make sense, and you can then host the html anywhere... there are 2-3 plugins that I saw, but I don't run a WP site so I can't comment on each.
This product looks like it'll do ops and stuff for you, so there may still be value if it just works.
Actually with those plugin you still have some drawback: first you still need to have and maintain secure the live WordPress installation somewhere, second you have to download the static version and upload it somewhere else, last but not least your contact forms and search will stop working.
The market will make sure that those ideas which are valuable solutions to problems people have will survive (if priced correctly). This means that problem solvers are compensated for their work so they can keep iterating. I don't really understand what your objection could be!
5 USD is super cheap. My coffee costs more than that and they're providing you with actual value. Pretty sure there are costs involved in running the infrastructure, fixing bugs and handling support
Come on, this clearly isn't yet-another-static-site generator for hackers but a commercial product for people who still use Wordpress, but not so foolish/desperate/cheap that they don't realise the security implications.