I think most people know what rust is, probably from other things than your shower head, which is a weird association as most people have plastic shower heads nowadays.
And yes, metal rusts, we've known that for millennia. It's a problem for everyone, including the navy and if you have a lot of metal, it gets expensive. This is no surprise and I think organisations like the navy have rust prevention factored in in the cost of maintenance?
Exactly what point is the author trying to make?
It could be a company that is trying to influence decision-makers to purchase their rust-proofing solution, it could be a political arm hoping to influence voters, or it could be a geo-political enemy hoping to sow distrust in the American military.
But ultimately, since the article does nothing but waffle between all the different ways that rust can mess with things, it's really just here to make you scared.
It may a different thing for people with municipal water; out here in the sticks everyone is on wells and this stuff keeps our white laundry brown and leaves lovely patterns on the insides of pipes.
Barnacles (and algal slime and so on) create significant hydrodynamic drag and damage paint, leading to rust also. Toxic chemicals are added to hull paint in order to repel them, but it is of limited efficacy and very bad for the environment.
I have often mused on the possibility of a small barnacle cleaning robot. Something the clamped and crawled with an electromagnet, a crushing/scraping barnacle doom. A number of systems out there, but none seem to have cracked the problem.
I have wondered whether a microwave would do the trick. Basically cooking the algae. The trick is then to access all the books and crannies, e.g. near the propeller. Unfortunately it probably wouldn't remove any barnacle polymer cement or other buildup, like the awful tube worms, you'd still need mechanical scrubbing.
With electrical techniques you also have to avoid magnetising the hull, which on navy vessels has been carefully degaussed.
Good journalism provides basic context.