I think this depends very much on how you use the tools.

My experience with email is that people have subject lines, email explicitly identifies to and cc recipients; email is threaded; email often has quotes/excerpting/highlighting from prior parts of the thread.

On the other hand, most chat usage I see is dependent on temporal aspects for threading (people under-utilize platform features for replies etc), tagging is generally only done to ping people to attract attention, chat groups are frequently reused for multiple different purposes.

Leaping to a point-in-time within a chat stream is often a bad user experience, with having to scroll up and down through unrelated stuff to find what you’re looking for.

Stuff in email is just massively more discoverable for me.

No, it has to do with context. In an email you will frequently have to provide more context for your answers to make sense. Chat is a conversation, which search drops you straight into, may with AI you could get placed at an appropriate starting point, but you're still reading a conversation. It's much easier to get dropped into a correspondence. To me the difference is like reading someones letter, vs. overhearing a conversation in a bus.

This obvious assumes that who ever wrote the email isn't a madman, who insist on using emails like it was a chat.

What makes email more useful in general is that each email is a separate object that you can organize in any way you want, i.e. move, copy, rename, sort into folders, attach as a file to any calendar entry, todo item, etc., or indeed to any other email. You can forward them to any other recipient, you can add and remove any recipient to and from the conversation at any time. It is conceptually powerful and flexible in a similar way that files in a file system are a powerful and flexible way to organize data. And it is easy to understand.

While all of these features could in principle be realized in a chat system as well, in practice they don’t provide that flexibility and power.

Another usability feature of emails is that they have a subject line. This allows to meaningfully list emails in a compact fashion. In a desktop interface, you can easily view and visually grep 50 emails or more at once in a mail folder or list of search results (in something like Outlook or Thunderbird or Mutt). This allows working with emails more efficiently than with a chat view where you can only see a few messages at once, and only of the same thread or channel.

Yet another usability feature of emails is that each email has its own read/unread status. This, again, is facilitated by each email being its own separate data object, and by the separation between subject and body, which allows the read status to be unambiguously bound to “opening” the email, or to navigating in the list of emails alongside a preview pane. And you can mark any email as unread again. In chats, the granularity of read/unread is the whole chat, whether you’ve actually read all of it or not. You can’t easily track what you’ve read or not in an automated way as with email, other than by that coarse-grained linear time-based property of when you last visited the channel.

Personally, when I send an email, I feel less time pressure to respond, so I more carefully craft my responses. The metadata is similar enough, but the actual data in email/forums is usually better.

> This is why, if something is important, I take it out of email and put it into a document people can reference.

This is how things should be done, regardless of which medium is used to discuss the project. Without isolating and aggregating the final decision of each thread, there is no way to determine what everybody has agreed upon as the final product without looking back, which quickly becomes onerous.

Things get messy when you start having different versions of each feature, but that doesn't change the concept of using email/Slack/Discord/text/etc. for discussion and a separate "living" document for formalizing those decisions.

We had this problem in our organization circa 20 years back so I built a ticketing system, now each conversation exists as its own object, and "the same thing being discussed twice" has the opportunity to be merged into one, etc. That seems to have helped a lot with our internal conversations.

Can't say for everyone, but I have terrible memory and rely heavily on the chat history (and other tools) to keep my mental model in shape.

Here, ephemeral means "this conversation might as well never had happened", so why waste time on that?

I really don't get why people are so happy about Slack (never used Discord). The interface is awful, it barely functions as a chat client, yet people adds bots, automation and use it as a repository for documentation. Honestly it would be better if history was deleted weekly or something, just to prevent people from storing things in Slack.

Were these ever ephemeral? Are you misremembering history free IRC chat rooms?

Slack is way worse than Teams. I honestly rather dislike both and rather use email only, but will pick Teams over Slack any time.