The difference to older tech like mechanical slot machines is that the game records everything the player does, and can then drop a "discounted" special offer at the right time to maximize the likelihood of keeping the player hooked.
There is also no disclosure as to if the odds are manipulated on a per player basis, which I believe there are a few patents related to changing the "drop" rate based on player behavior, this is similar and can be combined with your comment about monitoring to drop a discount at the right time
In the context of Diablo, I can not find the Odds of their loot boxes anywhere published.