Postgrahile allows you to rename/disable api endpoints if needed.
It's a great idea, and my clients and bank account agree with me.
There are lots of ways to do software. Some are widely considered by experts to be good, some are not so good.
Then there is a thing called business. You can certainly sell software that is built using bad practices, and honestly nobody will probably complain so long as it works. It might not be quite as maintainable, it might require more effort to add features, and it might be necessary to completely rewrite that software in 5 years when other parts of the system change.
Terrible software is bought all the time, and that's not even really a problem.
Even though you sold it and your customers are happy, there still are things you can probably learn, right?