>>39465633ok, so originally, TMs were single use universal moves. they were powerful, could be used on many pokemon, but because you could only use them once, you had to have pokemon learn powerful/different moves themselves.
today, it's to keep balance to the game, because powerful moves have been used already/previously, and for story reasons e.g. a weak bug pokemon evolving to its third stage at level 10 which is available before the first gym does not need to have a 90 power stab move as its signature move. sure you could teach butterfree psychic, but it gets confusion and psybeam (at best) to help with brock. it doesn't need more.
these days though, you do see a lot more pokemon learning 'good' moves, even if weaker because they realize this problem.
do you know how many Pokemon learned Thunder Bolt by level up in gen 1? A single one - Pikachu, and only in Pokemon Yellow.
Do you know how many learn it now? Many, many more.
