> Disclaiming HTML as a programming language when it is actually powerful for programming comes across to me as a No True Scotsman argument about "real" programming languages being used to program only in some contexts or to make only some things as the program.

I mean it's just about the traditional intent, and still oft-used understanding, that web browsers are viewers for hypertext documents. But sure, feel free to call GCC a "C browser" and .c files "c documents"