Absolutely

A site that doesn't work correctly without JavaScript should clearly notify the user. As much as possible should be made to work correctly without JavaScript. There are certain cases where this won't be possible, highly dynamic sites built on layers of AJAX and remote fetches are one of them. This doesn't mean that it's okay to show a blank page if I have JavaScript disabled.

Graceful degradation is extremely important, and it doesn't just apply to JavaScript, it applies to everything you code. Valid HTML markup, valid CSS, server side validation of everything.