Social/user-generated content (UGC) products like Instagram, Twitter, or TikTok are a type of marketplace: creators are suppliers of content for consumers. In most marketplaces, suppliers are trying to maximize revenue, but in social/UGC suppliers have many different motivations: some want to maximize audience, while others simply want to share with their family or friends. Different motivations require different incentives, some of which compete or conflict with each other. This makes social/UGC a uniquely hard type of marketplace to build.
Marketplaces work by aggregating suppliers and consumers into the same space. Suppliers have incentive to use the marketplace because the consumers are there and vice versa. Marketplaces typically grow by incentivizing suppliers or consumers to use the marketplace more. Increased usage from one side of the market often leads to increased usage from the other side as well. Incentive design is thus a major activity taken on by organizations that run marketplaces; it’s one of the most effective ways to grow.