While Lightning and Cashu are objectively inferior to main net Bitcoin, at the very least they are natively convertible to BTC and track it’s performance. Hence they are still better than any other completely separate shitcoin
Discussion
Cashu is a shitcoin by another name. It's literally an IOU that can rug you at any moment, infinitely and arbitrarily printable by the mint, and permissioned to redeem back your Bitcoin. It's a useful shitcoin. But you're still using a shitcoin.
If you can understand that then you can understand why other users find other shitcoins useful for other things.
Unless they claim those shitcoins being the superior form of money, I don't really care.