In that case (as is the case with most games) the near-worst case scenario is that you are no worse off trusting Valve with the management of item data than you would be if it was in a public block chain. Why? Because those items are valueless outside the context of the commercial game they are used in. If Valve shuts down CS:GO tomorrow, owning your skins as a digital asset on a blockchain wouldn't give you any more protection than the current status quo, because those skins are entirely dependent on the game itself to be used and viewed -- it'd be akin to holding stock certificates for a company that's already gone bankrupt and been liquidated: you have a token proving ownership of something that doesn't exist anymore.
Sure, there's the edge case that if your Steam account got nukes from orbit by Gaben himself along with all its purchase and trading history you could still cash out on your skin collection, Conversely, having Valve -- which, early VAC-ban wonkiness notwithstanding, has proven itself to be a generally-trustworthy operator of a digital games storefront for a couple decades now -- hold the master database means that if your account got hacked and your stuff shifted off the account to others for profit, it's much easier for Valve support to simply unwind those transactions and return your items to you. Infamously, in the case of blockchain ledgers, reversing a fraudulent transaction often requires forking the blockchain.
Science: knowledge workers stop being consistently productive past 40 hours per week, and probably less than that
Rentier-capitalists hot boxing their own farts recreationally: ackshually the problem is we let you dirty fucking peasants go home to sleep at all