Valve likely played a role in normalizing lootboxes in Western markets, but they definitely didn't invent the idea. MapleStory was doing lootboxes years earlier, and EA's Fifa was doing P2W lootboxes prior to TF2.

Their model of cosmetic-only lootboxes is also far less obnoxious than the P2W form that has taken over mobile gaming. Many mobile games today are designed to be as obnoxious as possible in the hopes that the player will crack open their wallet for a shortcut.