What is the benefits of declining payout?
Nothing because you decline "the benefit".
Some do this because they don't want to be rewarded out of ideology or because it would be inappropriate. For instance take Ned as example, he was the ceo of steemit. Should he be paid steem to make a message while it's supposed to be his job in the first place? A ceo is supposed to keep us updated on what's happening, he should not be rewarded for that. That's why he declines payouts.
