Because the word HOME and the ~ symbol are on that top-right key.
The Home key on the ADM-3A is also the key where the tilde is. Interpreting "~" as "home" means that there is a mnemonic for "home" built right onto the keycap legend.
Simply look more carefully at the key.
I see it now, lol. Thanks.
programmers are lazy and there's a ready made mnemonic right on the keyboard