But the idea of giving your stuff to other players is a more recent addition to the Magic playbook
Hemosymbic Mite Rating: 4/10 On its own, Hemosymbic Mite looks fairly weak, but its immensely annoying if the numbers happen to line up
If you were playing fair, there was no way you could compete with that if the deck pulled it off and many games were won simply due to a willingness to play a card this powerful, allowing such decks to win long games they would otherwise be lost in
And yes, I understand that in tournament play you're required to make it clear how each face-down card was cast, but that attention to detail is not extended to a lot of casual play
In the latter case, since the door becoming unlocked is what causes the ability to trigger, effects that cause abilities that trigger when a permanent enters to trigger an additional time (such as that of Panharmonicon) won't apply