I really want to sum this up and just say Japanese games as a whole, but I guess I'll guess give an example.
Collect all 7 plot items to help seal the evil Demon King
When all 7 are collected the Evil Demon King is freed - The Demon King wasnt that bad if they cant even get the legend right.
Then the antagonist force does the whole "hahahaaa we knew that happend hahaha" - So whyd you spend the entire game trying to prevent me from getting them then?
Then antagonist force is killed or taken over by Demon King.