While if I start a slack discussion, the thread is in once place, and everyone sees the state in real time, so the thread is more coherent and easier to follow.
Just recently I spent an hour unbundling a mail chain with layers of poor quote - reply - ask for clarification - further reply.
The way we use slack is start a top level topic and group all related discussion in a thread.
Same at my company: Top level comments initiate a thread, and all responses must be made as comments within the thread.
If I had my way, I'd take it a step further and require that Slack be treated like a message board, not a chatroom. If you have something to say, then say it all at once in one cohesive paragraph or set of paragraphs -- just as we do here. I do not want to be pinged multiple times in rapid succession while someone sends every thought they have in a stream-of-consciousness fashion, e.g.:
>> hi
>> can you help me with a problem?
>> i need to do x with y but i'm not sure about how to handle z
>> oh wait
>> nvm
>> figured it out
Awful.
I'm not saying email is perfect or always works well, it just seems to naturally work better more often in some ways.
> The way we use slack is start a top level topic and group all related discussion in a thread.
My company has not been disciplined about that, and even when threads are used new ones get started to continue the same topic relatively frequently.
Yeah, Slack is even worse than email for most uses. At least with email you have conversation threads that consolidate discussion on a topic that you can actually find later. My experience with Slack (and similar) that that everything gets fragmented immediately, to the degree that you can never put it back together again.
IMHO, Slack is only good for a few narrow cases (e.g. replacing long coordination email chains, organizing lunch).