It's their response to NIP-17. They basically created their own "GiftWrap", like we have. They shouldn't have forced the 2-hop step though. It's important that the forwarding relay ALSO can't track who you are sending things to. 

I would never use SimpleX without that setting on and I would NEVER use their own servers. Too bad those are optional things and not a required part of the protocol.

In the same way, never use Nostr with the default relays of any client. Educating users on the power of relays and allowing them to pick relays has to become a key part of using the protocol. Otherwise, we are just going to centralize again, which defeats the whole purpose of Nostr. 

BTW, they could have used Nostr relays to be routing nodes. They would have tapped a much bigger network of servers for their user's to choose from.