Here’s a sad but needed assessment from Max van der Schee: Why the adoption of Web Accessibility keeps failing.
While many rules for accessibility are easy enough to adopt in your code, there’s no hard stop if those rules are left out or miswritten. Your site still functions normally.
To help developers and designers attend to accessibility rules, Max shares a useful extension for Visual Studio Code called Web Accessibility. It gives feedback on what to change in your code to make it more accessible.