Ghosts of email past.

Why does email play a memory game for each reply, each time?!

Letters didn't have the concept of threads. Mail received each day in a mailroom would go to the relevant employee, get read, and have the required response drafted and sent through. The original letter would then either be put in the Archives room, or retained in the Inbox tray for any future reference.
Anyone choosing to forward the letter, would simply re-seal it, put a memo with their notes and send it over. CC - short for Carbon Copy - would literally be a version created with a Carbon paper underneath, to be sent to someone internally, for their knowledge. This worked fine, more or less.

Then electronic mail came along. Deriving completely from how physical mail were being handled, marked, sent and stowed back then. They built it considering that sending an email is equivalent to sending a letter. Only it wasn't.

Email, when initially invented, was constrained with modest processing power, limited memory and negligible bandwidth. Any design choice made due to these limitations, however, remained, persisted, and then dictated. Since the protocol allowed to send just one email object at a time (instead of an array), there was no way to send over the prior emails in a thread to a new recipient. How was a forward supposed to provide the current discussion to the forwardee who is now expected to respond? Well, they came up with a hack, and it uglified email forever.

"Why not just copy-paste all the prior emails, inside the new letter the user is sending?"
"But how would it know when it's actually needed? We don't know if the next recipient will end up forwarding to a new user!"
"Well, then let's paste it each time."

And thus, say hello to deeply nested, indented, and repeated blockquotes of all prior emails in every next email for every recipient in the thread, for all threads. They meant well, but they chose duct tape to fix a deeper problem. And now email has tape marks all over.

We are now used to this. We struggle in making sense of long email threads, but it's okay. No, it doesn't have to be anymore.

Faraday has arrived.