Because if you are on duty for production issues you may not be able to put your entire smartphone in do not disturb yet you don't want to be woken up at 3 am because some coworker send you something non critical.
Having separate devices for personnal and professional stuff helps. I can't speak about iOS, I used it way too long ago but both Android and most messaging platforms do not provide ways to have flexible do not disturb policies depending on multiple parameters such as sender/timeframe/app/format of message. It is usually a mix of the global do not disturb function for the OS, the global notification parameters per app and possibly some mute options on a contact/channel basis but that is not time range capable and only works on a blacklist instead of whitelist model.
On iOS the two most popular systems for on-call (OpsGenie and Pager Duty) both bypass DND if configured correctly so it's a non-issue. I imagine Android has something similar.
I would argue that, in most social contexts, “receiving a message” does put some amount of pressure on a person.
Unless you have a really explicit understanding with the person you’re texting, they’re gonna assume you expect a response, or just expect them to read the message.
You gotta know how your actions will be received; “I can’t help you” really just isn’t enough if you wanna be a kind and thoughtful person, IMO.
I disagree; a message sent on an async platform is not expected to be responded to immediately, it's simply meant to be removed from the sender's "to-do" list.
The distinction between sync vs async messaging isn’t as easy to figure out these days as it was when snail mail vs phone call were the primary options.
The negative consequences of making the wrong choice are both extremely low and extremely loud, so I urge you to just take a guess, with a strong bias for every technology platform being async.
Once upon a time, email was more generally considered to be non-interruptive, while a phone call and later sms was considered interruptive.
Ober time, this distinction has blurred due to technology changes and resulting cultural adjustments including immediate email delivery, voicemail and advanced messaging and notification systems.
And that change over time is causing some disconnects between expectations of good behaviour.
