A direct P2P connection over the internet is not private, as both ISPs can see who you're connecting to. P2P over an overlay network like Tor or I2P is better, but still not perfect: https://discuss.privacyguides.net/t/simplex-vs-cwtch-who-is-right/19256/8 I think many of those same points apply to I2P?
None of those points really apply to I2P. -Non persistant tunnels as opposed to persistent TOR circuits -The inproxy/outproxy model at minimum doubles the amount of "nodes" that would need to be captured for "unmasking" even then it is packet switched. -IRC routed through I2P is absolutely not like a TOR proxy.