So you are saying one shouldn't use JS to implement voting and comments but instead voting and comments should interrupt the video and then one uses JavaScript to restore the playback position. You also imply youtube should have waited for 6 years or whatever for video playback to even be possible without client side programming.
> Maybe browsers could even agree on a standard to refresh only part of the pages by querying the server themselves.
Maybe browsers could also agree on implementing all needed applications in the browser. Then you just make <youtube> tag and you have implemented youtube.