How do you identify if a message is of the 2.5 variety without first reading it to confirm it is not a 2? You still need to be interrupted to read the message. In my experience reminders have always been a way to manage work and not a way to manage notifications.
I misunderstood and thought you were talking about making sure you didn’t forget to fully deal with the message. I think it’s worth being notified about important messages, even if you have to deal with them later. If you’re truly too busy to triage Slack, the unread status keeps the message for you while you do non-chat work, or work out of an urgent channels synchronously and ignore the others.
>I think it’s worth being notified about important messages, even if you have to deal with them later
You are still misunderstanding. This isn't the problem. The issue is how to keep yourself from being interrupted from non-important messages. Slack provides support for messages that are not time sensitive. It encourages us to treat every channel as either worthy of some urgency to read or completely irrelevant and worthy of muting.
I guess I don’t see the problem if a channel notifies you and you either read/action immediately, or triage for later. Why is it a problem if your sender expects you to decide if you have time to deal with an important message now? If the message is long but unimportant, I’d file it in the “read quickly and move on” category. I think I’m disagreeing and not misunderstanding.
By default I turn all of my channels to Mention only. Other than that I have a few channels with low posting frequency which require urgent attention that I always have on notify. This gives me all 3 message types. I use the same pattern on Matrix and IRC as well.