The existing HackerNewsCollapse extension mentioned in the other comment already does this. I built a Chrome extension which extends this further by also trying

The existing HackerNewsCollapse extension mentioned in the other comment already does this. I built a Chrome extension which extends this further by also trying to summarize the comment thread based on word frequency of entire subtree (with mixed results) https://chrome.google.com/webstore/detail/hngist/jigimhmnilghciamfcdlogbaaokpakim?hl=en-US https://chrome.google.com/webstore/detail/hngist/jigimhmnilg... It also tries to come up with a summary sentence, but I need to do better sentence splitting. I don't think these extensions work on Google Chrome for mobile though..