It's almost the norm for threads to be into the hundreds or thousands of posts these days. For me, I'm actually more likely to click into a thread with like 20 posts on it because I know I can read it all. 200 posts in a new thread is daunting. 400 new posts on a thread I haven't visited in a while generally means I'm not going in there anymore because I'll never catch up. And even if I do catch up, I'll probably end up in the same situation down the road.

I know that key posts is/was a thing, but most threads have 0 and occasionally I'll see 2 or 3.

I think I'd be interested in condensed threads with just the highlights. The best thought I've had so far is: use the top 5% of posts in a thread as calculated by total thumbs up and down. (I think that way, you'd see the posts with the most thumbs up, most thumbs down, and most controversial ones. Basically, the ones that generated the most interest/reactions.)

Would this feature add value for anyone else?

Genius!

I do think an implementation that requires curation could end up with a slightly better result (but that requires a lot of dedication), but I think you could get 90% of the way there by just showing the posts with the most interactions (positive or negative). It's easy enough to try out: just go to a busy thread and scroll down quicky, stopping to read the posts with the most votes. It works quite well in terms of getting the highlights of the topic, but you spend a lot of time scrolling past noise.

That's a good point.

"Noise" was probably the wrong word. Off topic posts can be trashed, sure, but all the zero and 1 vote posts are contributing and don't need to be hidden from people who want to read the entire thread. And I'm happy to have those posts in smaller threads.

A cliff notes view would make me much more likely to open the many massive threads on this site that I shy away from. When I do click into those, my intention is just to read the first few posts, but then I get sucked in and several pages later am faced with the dilemma: do I drag myself through 10 more pages of this so I get the whole thing (and what's that spike in activity that happens 200 posts from now?), or do I quit probably to never return and wish I had stopped after the first few posts? Maybe I need more self control.