I was thinking as well, but seeing people's comment here I have understand where the campegn money comes from. It's just like an affiliate marketing or digital marketing where you advertise product online and create traffic on the site and hey paid for the work. Although signature campegn is better than affiliate marketing. because in affiliate you can only be paid on the people that use your link to buy goods from them, while signature pays you without people clicking on your affiliate link.
Exactly, you have understood it rightly.
That's how signature campaign works and that's why many companies seem to do it because it is effective for their brand. Sadly, the mixers won't be allowed to do any advertisement anymore due to what the admin decided to do. But affiliate marketing and signature campaign are different.
When you do affiliate marketing, you are forced to endorse a brand and make someone under your link, while in a signature campaign. You simply advertise.