Nah, I haven't seen it used for that. You can post content that's not yours, just site your sources. "Decline payout" was introduced because @steemitblog was posting updates and earning a large percentage of the reward pool. @steemitblog didn't want to earn rewards but if they wanted to post on Steem, they were forced to earn rewards.

Users also use it decline payout sometimes if they're just informing the community about something. @donkeypong sometimes uses it when he feels like he has earned too many rewards on his latest posts. @steemitblog declines payout every post. @dan and @eosio usually decline payout because they're using the platform as a way to get the information out there, not for the purpose of earning rewards.

I may have used it in the past when I was writing a quick post that I didn't feel like deserved any rewards, but it was information that I wanted others to know.