Can someone explain, why it has end-to-end encryption by default on this level, and why it is good? Isn't this project more about host discovery and routing. Is

Can someone explain, why it has end-to-end encryption by default on this level, and why it is good? Isn't this project more about host discovery and routing. Is it providing more performance compared to encryption on other layers, or just for "easy automatic" data encryption? Based on documentation, it sounds that they have some kind of own crypto implementation in the end. I found the whitepaper describing used algorithms, but I would need to know more how exactly they are applied and why they are selected, before I could trust the encryption.