That is true. But then we will be going into an intellectual rabbit hole of trying to determine what constitutes ``well-designed''.
While I'm personally on the opinion that ``well-designed'' mean that the object ought to be designed elegantly conforms to the designer's initial objectives and solves the problems he's trying to solve, some might take ``well-designed'' to be something completely different.
Given with what we know could happen with these things (i.e: HTTP), I think that a more thoughtful and deliberate approach would be more apt.
It might not help to use “elegant” when defining good design. ;-) But the point is certainly valid that the maker’s intention is key to evaluating design. It can be complicated, of course, that high-level design “how to achieve this” decisions are often expressed as if they are fundamental intentions.
Just for the record, I think the Gemini protocol is well-designed, *and* I agree with the intentions that design expresses.
Gemini text, on the other hand, neither expresses the intention of non-extensibility well nor do I agree with that goal.