We're wired to return the favor. When someone opens a door for us, our instinct is to hold the next door for them.
This generous response has led some marketers to aggressively take advantage. They do a favor for someone and then reap the benefits when the favor is returned. All under the guise of, "I'm helping other people."
“Helping other people” is not what they're doing.
What they're doing is hacking reciprocity as a tool to help them get what they want. They're trading favors.
Some people have had success with this, but please don’t denigrate the very human activity of actually helping others by conflating it with trading favors.