One of my first employers was at a public television station. In his mind, he had to ask the other party permission to link to them. That is thinking of a link as a physical thing, as if it was a copper wire or a metal house key. It's not. It's just information. Needing permission to link to something is exactly like needing permission to talk about something. That shouldn't be. If we live in a society that believes in free speech, we should all be free to link to anything we want to!