This article is my usual go-to and lists several reasons why JavaScript might not be available, and thus why you shouldn't take it for granted: https://piccalil.li/blog/a-handful-of-reasons-javascript-won...
- the user explicitly disabled JavaScript
- the browser does not support JavaScript (I sometimes view websites using elinks)
AFAIK screen readers also work better without JavaScript, so it's also an accessibility issue.
As I just said, users who explicitly disable JavaScript cannot even use Google Search. Why should I accommodate those users when even Google refuses to do so? They are actively choosing to have a limited web experience. The vast majority of the internet is completely broken for them.