I forget what the issue is there other than the obvious one of burning fuel to do that.

Suddenly I'm imagining a network of pipelines that just goes out into the ocean and has a bunch of small holes all along the way, like a massive array of soaker hoses.

I guess the problem with any of this is that there is going to be localized effects wherever you let the briny water out and it's just a question of how widespread and severe we decide to make it. :-/