How can reproduction take place in incomplete reproductive organs...hummmm??? Ask a fertility doctor what the requirements are for conception (male and female) and gestation.
The article talks about different reproductive systems that each work. They do not talk about incomplete reproduction systems. Are you headed toward that "irreducible complexity" nonsense?
Most reproduction is asexual. The "purpose" of sex is not reproduction, since that can, and does, occur without sex. Most organisms don't need any "reproductive" organs, complete or incomplete, to reproduce. You have confounded sex with reproduction.