There's a lot of evidence showing that gambling as a child leads to gambling problems as an adult, and loot boxes are just gambling aimed to a large degree at children.

Valve games are even worse for this because Steam trading allows 3rd party sites to sell cosmetics directly for cash, and some of these cosmetics are worth tens of thousands of dollars. It's just children gambling money but with a thin veneer of video game over the top.

Almost every game that has lootboxes, even only for cosmetics, is super stingy with cosmetics you can earn in-game through normal gameplay.