Self-custody Lightning is tied to an on-chain UTXO, yes.

But a custodial Lightning provider could just as easily create “paper sats” as an eCash mint could.

Bitcoin eCash doesn’t purport to solve everything. It’s still custodial, so a user can still get rugged and the Mint could still play paper games. Same incentives - and approximately the same risks - as a basic custodial Lightning wallet provider like Alby or WoS in this area. Gotta choose to trust a mint the same as you’d choose to trust Alby etc.

But eCash offers a significantly better privacy schematic than a standard custodial Lightning wallet provider. That’s the primary improvement over regular (custodial) Lightning.

It also can offer faster transactions and smoother UX in some cases, and the cryptography/tech (the little of it that I understand) is extremely cool.