(I appreciate that Kinder eggs are banned in the US, but not for that reason!)
It seems to me that the key thing about real gambling is that you win money. You put money in, and you might end up with more money than you started with, but probably won't. That's what generates the dynamic where once you lose some money, you keep playing to try and win it back.
With loot boxes, you put money in, and you get virtual goods out. The good vary, and there may be ways to sell the goods for money. But you're fundamentally just buying goods.
EDIT OF EDIT: This is the closest the article gets to touching on this:
> At least one case in the early 2000s had potential to resolve the issue of whether activity similar to loot boxes is considered gambling, but it was dismissed due to lack of standing. In Chaset v. Fleer/Skybox Int’l, LP, 300 F.3d 1083 (9th Cir. 2002), purchasers of baseball cards and Pokémon trading cards brought a RICO suit against, inter alia, the manufacturers and distributors of the trading cards. [...] The Court dismissed the suit for lack of standing based solely on plaintiff’s failure to satisfy this element.[26] It held that “at the time plaintiffs purchased the cards, . . . they received value . . . for what they paid,” and “[t]heir disappointment upon not finding [a rare] card in the package is not an injury to property.”[27]