It doesn't take a lot of genius, time, or money to set a link w/ url parameters or use a standard html form for e.g. upvoting or comment submission, and then override that with javascript for fancier UI / AJAX / avoid redirects, etc -- i.e., extra polish, rather than it being the only option and the site just becomes nonfunctional instead of degrading gracefully.
This benefits more than just one tiny group of users: it might also aid disabled users and accessibility software (not to mention the developers of that software), security nuts, people who turn js off to improve performance on low-spec machines (it's 2018 here, but more than a few countries have a four (or even three!) figure GDP/capita, so their machines aren't going to be 2018 machines. This is just off the top of my head, how many other groups might there be that would benefit?
You're thinking as a developer and not as a business. A website that works perfectly well for 99% of visitors and adds the pizazz to keep them on the site is the goal.
Will it help the businesses if they learned that plain web sites are easier to create (and update), are better for the users and needs less maintenance?
This benefits more than just one tiny group of users: it might also aid disabled users and accessibility software (not to mention the developers of that software), security nuts, people who turn js off to improve performance on low-spec machines (it's 2018 here, but more than a few countries have a four (or even three!) figure GDP/capita, so their machines aren't going to be 2018 machines. This is just off the top of my head, how many other groups might there be that would benefit?