complementation - Why is "He knows to swim" incorrect?

I was reading a website where common English sentence errors are written -

INCORRECT - He doesn't know to swim.

CORRECT - He doesn't know how to swim.

I know He doesn't know how to swim is a correct sentence. But why is the other one wrong, is my question?

I know that know is a transitive verb. So, the following are correct -

i) He knows swimming.

Swimming is a gerund. We can also use the infinitive form here - to swim

ii) He knows to swim.