So what exactly is the reason that i2p has thus far elected not to have a system of “exit” relays which allow users to access the clearnet?

Every time it comes up the question is deflected by saying that i2p is not meant to help anonymize clearnet traffic, but to be its own independent network. But why not both? If it is just not the devs interests then that is what it is, but I’m surprised people in the community really wouldn’t want to be able to use i2p to anonymize their clearnet traffic.