Vivialdi.com blank if JS disabled
That's not exactly feedback on the browser itself but on the first-time experience when visiting vivaldi.com. It makes a bad impression if the browser's homepage stays blank if JS is disabled. At least a comprehensive error message should be displayed. But actually, I expect a site to offer its core functionality even without JS - given it is not some web application page. Accessibility!
Webpage shows up on a non JS text browser like lynx or w3m. Therfore it is not really a accessabiliy issue.
But a "normal" user should be alerted about missing JS.
I agree: a website should be accessable without any active content!