“Specifically, Legendary Gems aren’t even a guaranteed drop for paying players, as they are only randomly awarded upon purchasing Legendary Crests (i.e. loot boxes) - which may be the reason why Diablo Immortal didn’t launch worldwide.”
Free to play means free to watch other people pay $110,000. Top-rated gems can’t be earned without spending, and a free player needs about 10 years to max a character. Even the whales are buying loot boxes, not gear. Blizzard built a slot machine and skinned it as Diablo.