> the TUI designers will be more tightly clustered together because the TUI interface constrains what's reasonable.

It constrains what’s possible, not what’s reasonable. For example, one could typically fit more text on a screen by compressing it, but most of the time, that’s not the reasonable thing to do.

I’m saying most of the time because of the existence of English Braille (https://en.wikipedia.org/wiki/English_Braille#System) which uses a compression scheme to compress frequently used words and character sequences such as ‘and’ and ‘ing’ shows that, if there is enough pressure to keep texts short, humans are willing to learn fairly idiosyncratic text compression schemes.

colorforth (https://en.wikipedia.org/wiki/ColorForth) is another, way less popular example. It uses color to shorten program source code.

One could also argue Unix, which uses a widely inconsistent ad-hoc compression scheme, writing “move” as “mv”, “copy” as “cp” or “cpy” (as in “strcpy”), etc. also shows that, but I think that would be a weaker argument.

> It constrains what’s possible, not what’s reasonable.

Why do you say "constrains what’s possible, not what’s reasonable", as though it's one and not the other? Does possibility conflict with reasonability? I would think it's not an either/or, it's a both/and.

The set of reasonable things is bounded by the set of possible things. So if the constraints of TUI design make certain things impossible, surely they make those same things unreasonable at the same time.