I don't know that it's easier to game so much as people don't tend to spew toxic garbage when they suspect someone is gaming them. There's decorum.

I have no idea if there is pro-Google astroturfing happening on HN, but there is definitely pro-CCP astroturfing happening on HN in every thread with even a tangential connection to China. So it would not surprise me if huge corporations paid for services which may include astroturfing.

It's easier to game because it has minimal verification procedures and much less traffic, and the tech being used is way less advanced (and mods are less active).