Problem: Department stores sell TMs. IIRC a character, not sure in what gen, says something like "An attacking move, or a defensive move?", implying they are considering buying a TM. Also, the guy in the burgled house in Cerulean says he "decided to teach Diglett to Dig without using a TM", implying that he would have been entirely able to use it.
Since in RBY it's strongly implied that Red and Blue are the first people to use Pokedexes, the idea that TM's functioning depends on the Pokedex doesn't work out.
"If I may guess, Emboar might be an exception to the norm that the scalding liquid is expelled from the Pokémon's mouth" - Cobraroll, on Emboar learning Scald.
"Nothing like a cup of tea to start off the day" - Professor Oak, EP025.