It isn't. At least not and also allow common hardware node runners to participate. This is a real discussion that's out there. You should check out your local bitdevs you'll learn a lot.

So anyway that's why we look at L2s that allow for sharing a UTXO and use L1 to settle disputes over it. Under more drastic measures where the UTXO set really is just too large for common hardware... Some less than desirable solutions and who knows maybe a desirable solution one day will have to be performed to preserve decentralization.