Tor's take on the common proposal to do this is at

https://2019.www.torproject.org/docs/faq.html.en#BetterAnony...

and notes this threat model issue:

> There are some cases where it doesn't seem to help: if an attacker can watch all of your incoming and outgoing traffic, then it's easy for them to learn which connections were relayed and which started at you. (In this case they still don't know your destinations unless they are watching them too, but you're no better off than if you were an ordinary client.)

(I'm not mentioning this to criticize I2P's design, just to point out that the benefit you get from this decision depends a lot on your threat model!)