The thing about sticker packs, Pokémon cards, etc. is that you could trade the ones you didn't want with your friends, so even getting a shiny that you already had was exciting because then you had something that you could swap for another shiny or a couple of lower-value cards/stickers. You'd naturally come to the point where some stickers were much more frequent than others so you'd end up with this little schoolyard economy where everybody knew what was worthless and what wasn't. Once your collection is complete there's no reason to buy any more. Hell, some of those things even become collectors items and retain some value over time.

Loot boxes strip all of that away and introduce FOMO, so the only option you have is to keep pumping money into the machine, and then to up the ante if everyone else starts getting skins or emotes or dance moves that you don't have, so you don't get left behind.

What's more is that they're linked to micro transactions, so there's nothing stopping you throwing away as much money as you have in your bank account, or having your kid do it without any awareness of where the money is actually coming from. Spending £1.50 of your pocket money on a pack of stickers is a totally different situation to blowing £10-£20 a pop on in-game currencies to buy loot boxes.

There are few things that I'd call evil but this stuff is beyond malevolent. At best it's a shameless scam and they go to an incredibly effort to make the vanilla game boring without buying into the gamble.