Base info: I'm a front end dev born in the early 90's with three years experience.
A lot of older dev's that I've worked with have told me that best practice often includes making sure that the site is usable even if you've got javascript disabled.
To me, this is completely bonkers. Are we really supposed to cater to the sub 2% that chooses not to use javascript?
To me it would make more sense to use that time to make the sites usable for visitors with disabilities by including screen reader support and stuff like that.
Because not all search engines could cope with it (this reason now obsolete).
Because of a variety of screen readers and browsers which don't (reason also obsolete).
It's good practice to not go with batshit insane navigation, however (infinite scroll interactions with the back button, anyone?), or require JS for trivial inanities, or not have relatively meaningful URIs.