Overlay mix networks such as Tor and I2P protect IP address information from passive adversaries and increase the cost of active attacks. However, many users will be unable to connect over these transports and low-latency mix networks are unable to defend against a wide number of attacks (a global surveillance state is explicitly excluded from the Tor security model). They also tend to complicate analysis of sybil attacks against client software.
Which is to say, Tor is necessary but insufficient to protect privacy at the transport level. Thankfully, cryptocurrency transactions do not have the same low-latency requirements.
I sifted through the Github tickets and forum but did not find any discussion on this topic. Am I missing anything?