Want to use IPv6? Fine. But don’t try to remove v4 support from people who have built stable networks around it.
You won’t be able to force the world to switch to IPv6 with tricks like this, any more than you can force old industrial machines to stop using ancient 486es as controllers. There is a lot of old equipment in the world.
IPv6 was built to work alongside v4, and there is no reason to change that.