I feel like the lag-time of communication was an important component of older forms of communication that has been lost. That's not to say that fast communication isn't a boon to society, of course. Only that slower communication gives you more flexibility in how you respond, and more time to think about what your response should be.

When the main form of long distance communication was the postal system, and letters took days to travel from sender to receiver, you could easily wait days, if not weeks, to draft up your reply and mail it out. The recipient on the other end wouldn't even be able to discern the difference between your delay and the delay from the postal network itself. It had some in-built slack.

When the only phones were landlines, if someone called you and you knew you were in a bad mood, the kind of bad mood that would invariably make you say something stupid, you could just not pick up! There were plenty of common, understandable reasons someone wouldn't be available to answer their landline. Then they could leave you a message, and you could call back when you mood improved again. Again, there was slack built into the system.

Now there's this cultural expectation that puts far more attention on your reaction speed. A text message with no immediate response could just be them not seeing it immediately... But actually no! Now we have read receipts too! You can't even pretend to have not seen it yet while you think of your reply. Some platforms even have the little "currently typing" indicator tell them how long you've spent drafting and re-drafting whatever message you ended up sending. A panopticon of communication. Now there's no slack. Any person anywhere in the world could try and get a hold of you with the same expectation of immediacy that a face-to-face conversation would supply.

Now of course, not every single person I might text, call, or send an email to, will have the same expectations for what is an appropriate degree of responsiveness. But, (speaking from my personal experience) I am absolutely miserable at reading that from social clues. I am left having to assume that, in the absence of some clear indicator to the contrary, whoever I am writing to will actually have rather strict expectations, and that allowing myself to be lax may very well give them a terrible opinion of me. (Though, the degree to which their opinion of me actually matters is a different question entirely!)