Once you make an interface accessible, it becomes much harder to change that interface and add new functionality while maintaining accessibility.

This is why tech first finds an interface that works and makes money, and then turns around and makes it accessible.

Succes requires quickly testing if something works at all. Those tests don't need accessibility to be accurate, so they don't have accessibility.

What is important is that, when you found that something works and you start profiting from it, that you make it accessible. incidentally, this is how the EU law works aswell.

I think it is safer to say that accessibility is an one of many edge cases. Not important ... until it suddenly is.

I had many tricks to "sell" accessibility to the various clients and one of them was "What percentage of your potential users would you like to immediately piss off?" "How comfortable are you with random lawsuits? [Then you have to talk about the Target lawsuit]"

And furthermore, that accessibility is useless.

Not really.

Solving a new problem / use case is going to help you be successful, accessibility isn't novel. It's a feature.