I don't think programmers are the issue here. What you describe sounds to me more like the typical product management in a company. Stuff features into the thing until it bursts of bugs and is barely maintainable.
I would love to do something like what you describe. Build a simple but solid and very specialized solution. However I am not sure there is demand or if I have the right ideas for what to do.
You mention invoicing and I think: there must be hundreds of apps for what you describe but maybe I am wrong. What is the one good app you mention? I am curious now :)
There's a whole bunch of apps for invoicing, but if you try them, you'll see that they are excessively complicated. Probably because they want to cover all bases of all use cases. Meaning they aren't great for any use case. Like you say.
The invoicing app in particular I was referring to is Cakedesk. Made by a solo developer who sells it for a fair price. Easy to use and has all the necessary functions. Probably the name and the icon is holding him back, though. As far as I understand, the app is mostly a database and an Electron/Chromium front-end, all local on your computer. Probably very simple and uninteresting for a programmer, but extremely interesting for customers who have a problem to solve.
I would love to do something like what you describe. Build a simple but solid and very specialized solution. However I am not sure there is demand or if I have the right ideas for what to do.
You mention invoicing and I think: there must be hundreds of apps for what you describe but maybe I am wrong. What is the one good app you mention? I am curious now :)