This is literally the answer.

Different attempts have been trying to convert tidal and wave motion into energy for decades and the issue has always been corrosion and maintenance, and the costs related to both. The closest I've seen to a simplified energy capture device are those wave motion devices that move back/forth from ocean currents similar to how sea weed or kelp move. Grid connection and storage are both still a pain, but at least it's not a turbine in salt water.

It's like mineral oil cooling for PCs. Yes, it's doable. No, it's not worth it except in those rare edge cases.