None of these are in the oceans i believe. Instead they're using a sea that's between UK and mainland europe

It shouldn't be a deal breaker, but doing the same on oceanic water will have it's own challenges with significantly higher wind variance and more flotsam dangers

You claim of offshore wind being “cheap” relies on data from the north sea.

A region of:

- no freezing water, no icebergs

- few, low intensity storms

- shallow seas (often less than 100 m)

- surrounded by wealthy nations with large population centres

The argument does not hold and does not transfer well.