You’ve replaced “read” in the first part with “agree” in the second, and those are not at all the same thing. I can’t let you know that I haven’t read your message.
If a parent says to the other “hey, I’m running late, I need you to pick up Tiny Tim from school”, an acknowledgement is paramount even if you read, understood, and agreed to the message.
> it's just The Generals Problem.
That problem is concerned with an unreliable communication channel, which does not apply to the situation.
The problem isn't the acknowledgement, it's the additional steps I have to make to acknowledge the acknowledgement to the email system.
Eg Whatsapp has 1 tick for sent, 2 for received, and turns them blue for opened.
For example, if a sergeant says to a private "It's a nice day outside.", the private is obliged to respond, even if the statement is rhetorical. This leads to perfunctory responses, in this case it would be "Aye aye sergeant", or "Aye sergeant", or more casually "Er" or "Kill". You're not obliged to agree, just to acknowledge. Pretty similar to tapback responses in messenger apps and emails.
Sure, there's norms around how you talk on the radio, standing watch on the bridge, on chat channels for command and control, etc. But the rest of the time, the rest of the military talks to each other more or less like normal people with the addition of acknowledging relative rank.