Why is Clamperl a gender-segregated Linking Cord evolution when the Deep Sea Tooth and Scale exist?

Those items exist for the sole purpose of evolving Clamperl, why are they not implemented? As far as I can tell most other "trade while holding x item" evolutions just uses x item like you'd use an evolution stone. The only exceptions seem to be Onix into Steelix and Scyther into Scizor, since Metal Coat is also the held item that buffs steel moves, so they instead use the Linking Cord and need to know a Steel move to evolve. I'm not seeing any reason Clamperl's evolutions have to be done like this though.