Back in the old days (2007) it was necessary to manually type-out:

@whomever YOU ARE WRONG AND I HATE YOU!

…in order to reply to a Tweet; replies were denoted by @ being the first character of a tweet.

This also presages putting a dot — as in .@whomever — at the start of a reply to make it a “public” or “open” response.

I am astonished that nobody (?) has yet demanded to return to this Year-Zero state of innocent grace in order to reduce “online harms”, much like putting pills into blister-packs in order to reduce suicides by making it harder to neck a bottle of paracetamol.

Do join my campaign to add a reply button to tweets on Twitter: http://tinyurl.com/3c45f7

— Alec Muffett (@AlecMuffett) September 5, 2007

The TinyURL still works, and links to this article:

My Idea I Submitted To Twitter: A Reply Button