Public websites that are backed by government institutions must comply to certain accessibility standards for people with disabilities. US federal agencies are required to comply with section 508 of the Rehabilitation Act, the EU is on the process of making accessibility a legal requirement, and many other governments have already chosen to do so (like Spain since December 2005).
Accessibility requirements in its current form obligates your website to be usable without requiring the user to have javascript enabled. This may change in the future, as an increasing number of javascript frameworks incorporate ARIA roles to their generated HTML code.
Even if your case is not required by law to be accessible, you may want to support the following use cases:
Loom helps under the hoods with some concrete cases:
Further discussion on this topic can be checked out here.
Loom is a member of the European Accessibility Portal.