The only way this even tries to make sense is by creating the idea that the obviousness of it being a security (you're lending something of value to an enterprise in hopes of generating return) doesn't count, because it's a computer or something.

Like if the exact same thing was accomplished by people it's obviously a security but since it's done by code (which was magically and immaculately conceived, presumably) then it's different somehow.

It's not different. Coinbase wants people to give them money, have them do [complicated thing] then give them a return on that money.