William didn't advise the leader of this city out of his pure will or kind heart. He wanted to save lots of trouble for his guild branch here and his people. If this city started to act openly to gather all the new intel and information, memories and things that no one knew before, then it'd save his branch a great deal of time.
As the leader got what he wanted, William was sure such a greedy leader wouldn't let such a chance slip by. But first, he had to test out the true value of this information and knowledge. And the moment he'd do that, he'd start madly gathering up all the information he could from not only this continent, but from the entire world.
William knew such a move would definitely attract tons of attention later on, starting many cities and forces to copy this city's move. He didn't care about that, as he was sure by the time others would move, this city would collect enough to let it rise up for many stages over the heads of others.