This is not universally true. All of the US cards I’ve used on non-US websites, probably multiple times a week in multiple European countries for years now, have worked either without a billing address (if the website doesn’t support it) or sometimes even with an incorrect billing address, such as a non-US address for US card. Most websites in western European countries seem to support it so this usually doesn’t come up but I’ve never had a problem at least with my current cards when it does.

The only time I did have a problem is when no foreign card was accepted by the payment processor, not due to verification issues.