When effects never activate when they are sent to the graveyard as material or tributes. The reason is, in order for a when effect to trigger, it must be the last “event” in the game to happen.
When you use a monster for a tribute summon or set, you tribute your monsters, THEN you perform the summon or set of a monster. The last event is not the monster being sent to the graveyard, but a monster being summoned/set. This is the same for any extra deck summoning that isn’t apart of a card effect. This is how you can activate Trap Hole. It is also a when effect yet activates when you perform a tribute or normal summon that isn’t apart of a chain.
This is how the game has always been played.
As further proof, you can see the guide that outlines this exactly in the Summonings and Timing paragraph listed here: YGOrganization | Demystifying Rulings, Part 6: Summons