I think you're not giving yourself enough credits and you're giving Rails too much.
I know a developer who followed a similar approach in PHP.
A relative of mine is running his company as a single dev in node.js + react.
My company runs on Python.
The key skill is being a good generalist willing and capable to do all the roles you need.
Every tech stack can be automated for most small business needs, so that you can reduce the time spent on it.
I agree. Nothing beats using a well known framework for speed.
I think we also need to consider how much experience one has with a language. Most can pickup a new language relatively quickly, but it's not the same as having real experience with it.
At work, someone just started a new micro service written in Rust because they were familiar with Rust and thought they would be able to do something "fast". They spent at least half the time struggling with even basic dependencies, how to deploy it, monitor it and make it deployable. If this was a startup, they would have burned a significant amount of time that could have been spent on PMF
I know a developer who followed a similar approach in PHP.
A relative of mine is running his company as a single dev in node.js + react.
My company runs on Python.
The key skill is being a good generalist willing and capable to do all the roles you need. Every tech stack can be automated for most small business needs, so that you can reduce the time spent on it.