If someone that has some high reputation/is your friend/etc, explicitely asks you to do something, it definitely is manipulation.
I would disagree that all requests are inherently manipulative simply because they come from a friend or a person with a good reputation.
Asking someone to review something is neutral a non manipulative.
Asking someone to take a position according to yours is manipulative in regards to the decision making.
I'm not a complete naive and I know that's exactly how the world works. The more friends you have, the more votes you get. But let's just call it what it is, shall we?