The parent suggested HN as an example of an application that didn't need a lot of client code. I think its still fair to say that it doesn't have many of the features that ordinary users have come to expect.

Old reddit is a much more reasonable suggestion. It is fairly feature rich and is used by a large group of users. It seems to deliver ~340KB of Javascript. It's pretty nicely minified so I can't tell what its all related to but at least some of it must be related to the interactivity that HN is missing.

Like I said in my previous comment, you can do as old Reddit did and build up Javascript to solve these problems but at some stage it might make sense to jump to an SPA. Reddit made that decision. I think many would argue that they prefer old Reddit which is fair enough.

I think its hard to say if the Reddit team made the decision based on a legitimate and provable technical need and their old solution just wasn't cutting it or if they went the SPA route because "its what everyone else does" and "its easier to hire React devs".