Chats are ambiguous because it functions both as sync and async. I treat my whatsapp messages as async, but time and again I get heat from people because I take too long to reply, something I'll never feel the urge to apologize for.
Or maybe your agreement with your spouse is to communicate over instant message about managing these daily tasks, in which case it's ok, but you better crank that notification sound all the way to 11 LOL
My point is, there are types of messages which are highly time sensitive to the point where the response is meaningless past a certain point, and to many in this day and age instant messaging is the format for such inquiries to be made. Sure, one could be busy and be unable to respond, and one should be understanding of that. But it the reason why my spouse was unreachable was because they didn't bother responding to me at that moment to an obviously important time critical message we've got some problems in our relationship to figure out.
Ah yes, understood. That makes total sense. In fact I was thinking about a practical system that could be used to bypass silent modes and do not disturb configs for such emergencies. Back when MSN was a thing you had a buzz button that would play an alarm, vibrate the chat window and steal the window focus. It was as amusing as it was annoying, but there are practical uses for this.