It's not terribly complex, and it's all scripted. I don't like my identity being trackable across services, or across areas of my life. For instance, dickheads have created databases of public keys scraped from services like github, which can be used to identify the vast majority of github users whenever they ssh into some other service. By default, the ssh client will try to authenticate with every available keypair until it finds a match, which can further leak information about you(r machine).