Nobody has made that argument. It's not something they "HAVE" to do... it's something they should have done.
No. It's not a question of something "being learned". The lack of a Green Steel Greataxe in Module 6 was not because nobody tried putting a Splintered Horn into the Altar Of Fecundity. It simply didn't work back then.
It's not something that was learned, but something that was observed when it changed.
That position is wrong in many ways, but I'll just tell one of them: This is not real life. It's a game, and we're paying for it to be fun.