[sudahtigabulan]

> I don't think it's even so much about keystroke count as it is the "commands" are more like a language

It was about minimizing the number of redraws, but this indirectly might have led to fewer keystrokes too.

As you mention later in your comment, there are a lot of motions (which could be combined with deletion too). This is probably related to performance too, because they make it possible to achieve something quite specific like c3), with only a single redraw, and three keystrokes.

The "language" is undoubtedly a very good choice on part of Bill Joy. It wasn't necessitated by the hardware constraints, I believe. The separate modes neither. It's just that he would have wound up with less ergonomic key mappings.

Without the modes we would have to suffer using chorded shortcuts with modifiers, but they could still form a language. Think "M-3 C-d C-)" instead of d3).

Without neither modes nor composition (the "language"), it would have been even worse. A large number of single-purpose shortcuts, likely with multiple modifiers; he would have run out of (memorizable) single modifier combinations.