Of course that's up for the developer to decide. You can't force a developer to make a website accessible to all people regarding of their capabilities.
But you have to remember the initial goal of why the Internet started as open and what was the initial goal, to make all information accessible to everyone, that's why accessibility standards were there since the beginning.
That was the entire goal of the web, to be open and accessible to EVERYONE.
But if you want to go full head on capitalism and argue it doesn't matter for business, accessibility is literally search engine optimization, which is great for business. Googlebot is blind and doesn't use a mouse to surf the web.
From any perspective Accessibility is a requirements for any website or web application. Of course, nobody can force developers to make websites accessible.
Wait, yeah they can:
* https://www.reuters.com/article/us-usa-court-dominos-pizza/u...