Valve didn't invent lootboxes. The concept has physically existed for decades, they're called trading card packs or kinder eggs or gashapon. The latter is the inspiration for what became known as lootboxes. The first "lootbox" was actually in the Japanese version of MapleStory in 2004 and it spread in eastern markets (because pay to win is more normalized there) and in mobile games. It wasn't until 2009 when EA added card packs to FIFA. Hard to say if they were inspired by the lootboxes from the east of the insane football trading card market in the west, or by both. It was only after a year and a half later in 2010 when Valve added loot boxes to TF2. So Valve definitely didn't invent lootboxes, they weren't even the first in the west to use them. You could argue that they popularized loot boxes but even there is an argument to be made that Overwatch was a much bigger cultural hit than TF2 or CSGO or EAs FIFA games and normalized lootboxes.

I don't mind the "Valve is bad" narrative, but at least keep your facts straight. The "strongest DRM" is also BS but others have already somewhat covered that part.