Worth noting that you don't have to be a Ruby person to effectively use Jekyll. Most of the dynamic features are implemented in the Liquid templating language -- I hardly ever touched any Ruby when dealing with Jekyll, especially if I were using it in conjunction with (typical) Github Pages, which whitelists Jekyll plugins and thus incentivizes sticking with the simple vanilla setup.
I'm not a ruby person but I use Jekyll for a lot of projects. What I can't do is write plugins, but you should really have strong custom requirements to need a plugin.
I know Ruby, and was recently a business "can't write my own plug-ins" person. If you have a plug-in need that would be handy for you, feel free to ping me. For fun, I'll craft you a demo that incorporates what you'd need to know to write that plug-in yourself, with source code and a how-to Youtube video!
After having to "blow it all away and start again" a few times myself, I now use Jekyll via Docker. Jekyll themselves take care of all the dependencies and my machine can stay clean.
That's true, but if you're a relatively seasoned developer, the ecosystem is stable enough that you can manage. By "stable", I mean, being able to run homebrew and install something like rbenv. I can't remember the last time Jekyll up and failed on me, but for other projects, it's straightforward to blow away a Ruby install and start clean.
Admittedly, I'm not sure how easy it is to find canonical Ruby management tutorials when starting out. I think Ruby's system is somewhat simpler than npm, but only because I don't do too much with Ruby and don't often need to change things around.
