I think the hook is the same with loot boxes, gacha and booster packs. You pay money for the thrill of not knowing what you are going to get. For some people that thrill is addictive, so they keep spending more money for that brief moment of excitement.

From my perspective the idea of a game being compelling because of the mystery doesn't work with PvP because the fundamental mechanic pushes people to learn the meta so they can win. If the original goal of Magic was to allow people to feel the wonder of discovery, either it should have been a PvE game with a GM, or the booster packs actually are a core mechanic that provide the thrill of the unknown, in which case the game was structured from the start to make money.

Boosters were in from the start, and that means the gambling and "skinnerisation" were already there, perhaps less optimised than today but fundamentally the same thing. Whales buying every booster they could get their hands on until they got the cards they wanted was something that happened as soon as it went on sale.