Because it's a federated network, you'd need 11 people to collude to rug you. With wallet of satoshi, that's full custody, only takes 1.
Why is it safer than full custody?
I just set up a nostr:npub1jg552aulj07skd6e7y2hu0vl5g8nl5jvfw8jhn6jpjk0vjd0waksvl6n8n Jade about week ago. A bit different UI than I'm used to with the QR code option. I haven't played with L-BTC at all. Also had some issues setting up my watch only wallet in the Green app.