To be frank, lootboxes are gambling, and Steam is a functional monopoly.
(Note that being a functional monopoly and being an exploitative monopoly are not the same thing, though it does get complicated when you consider all the laws of all the countries in the world)
I think this particular lawsuit is legitimate and should proceed.
But!
The other part of that is that Valve is basically the only major player in the gaming space that isn't currently completely imploding or massively downsizing or dissapointing investors or having to get bought out by foreign royal families.
So, they all really hate that Valve can 'do nothing', and continue to win.
Valve doesn't have a board of investors... they're a private company, that's their secret sauce... and... all the other publically traded gaming companies?
You got a whole bunch of people who sit on multiple boards, of multiple different companies in the space, at the same time, and/or just cycle through actually working for one of them in an executive position and bounce around from one company to another, every roughly half decade.
They either know each other or literally are the same people, and functionally constitute a big club, that Valve isn't part of.
So, those people can work together, literally conspire, to pull various levers in various game industry lobby groups, and talk to other people to convince them they should really go after their shared, common competitor.
Corporate tactics.
Losses from legal outcomes are literally a cost of doing business: These people factor that in to the moves they make.
They do not 'play fair'. If they did, they wouldn't be on these boards.
Ironically... you can describe and model this kind of behavior, tactics and strategy... with game theory.