I like how Slack hides threads. But I do have a few complaints.

I don't like that you can't come back later, select a bunch of messages or threads and say "Group into a thread" to clean up people not using threads.

Also I kind of hate when it's a week later and someone responds to a thread and you get pinged, but can't find where you got pinged from without clicking the dynamic group to see all thread activity.

Also, it really annoys me that threads open on the right with the text entry on the lower right when toast notifications on Windows pop up on the lower right, too. Great, now whenever someone replies I get a toast popup blocking me from seeing what I'm typing. Thanks, guys. Sure, that only happens on one monitor, but that's also the same monitor that I want my toast notifications and my Slack to be on because it's where I'm often looking.

I wish Slack had a notion of Threadmaster(s) on a channel who could drag other people's messages into and out of threads. Because with people who aren't familiar with Slack or aren't committed to threading, you end up with a split brain between the conversation in the thread and the conversation at the top level. I get that it's hard from a permissioning perspective since anyone can create a public channel, but this should be a solvable problem.

They fixed your second problem with the thread tab, which shows all threads you are part of. I find that pretty convenient since it sorts threads by the latest message added, not sorted chronologically by the first message like it is in the normal view.

I also think it's problematic (and, granted this might be more on users than slack) - that a thread off an @here comment pings everyone in existence on every reply. Maybe I just wish our admins would turn off @here for general usage though ;P

Same here, if you don't hide the thread then what's the point? Some technical discussions in our team board last for hundred of messages, without threads it would be really hard to follow the channel, especially with multiple discussions going at the same time.

If you've used Flowdock, the point is that you can focus by going into the thread, by but you can also just view all the messages as they come in so that you're not missing anything on a channel.

People also learn to use threads quite fast. You can rethread comments if they don't have a reply yet (they are not in any thread yet).

Yes, this is exactly what threads are for. To get a side conversation out of the way.

I'm sure this is an atypical use case, but I found the hidden threads really useful for creating spoiler threads about TV shows/movies/etc. All discussion about the topic can stay inside the thread, and folks who want to avoid spoilers can simply avoid clicking on the thread.

Isn't that what Discord's spoiler tags are for?

It's discouraged on some Slack servers though, because it's pretty terrible for accessibility.

I'm not familiar with the accessibility, but this seems more like Slack needing to make the feature more accessible than saying that the feature is bad.