Instead of requiring that, a better alternative is: You can still use software that doesn't comply, and commercial organizations can write software that doesn't

Instead of requiring that, a better alternative is: You can still use software that doesn't comply, and commercial organizations can write software that doesn't comply, but then they can't call it a compliant web browser program. (This way, the user is properly informed what it is.) This way, it won't stop anyone's freedom to do something, especially that of the user (who might or might not also be a programmer). But I think WWW is too messy and complicated. Better is to not require a web browser at all, if it can be avoided. (There is also gopher, telnet, postal mail, etc, depending what you need. The web pages can still be provided as an option, of course.)