WhatsApp Behaviour When Deactivating

I recently quit Whatsapp - I decided not to make a fuss (nor did I want to take the time), and just deactiviated my account and removed the app. Unfortunately for my social graces, I did not think much about how Whatsapp would handle my existing conversations. To my surprise, it put a "xxxx has left the group" in all of my group chats, but has put no indication at all of any change in any of my one-on-one chats. All that happens, apparently, is that someone who messages me now gets a single check mark "not delivered" status.

This seems completely backwards to me. To my friends, I have rudely left all of the groups I was in (and even if I knew about this, I wouldn't want to go back through all of my groups and leave a polite message).

I'm especially surprised that, for other users, there is no difference between me having my phone off, and having deactivated my Whatsapp account. Unless I took the time to tell everyone "I'm leaving Whatsapp" (which seems quite tedious), it now looks like I'm ignoring everyone.

Whatsapp - why are you so rude to the friends of people who leave?