Why does Indiegogo ask for a tip?

Why does Indiegogo, a popular crowdfunding platform, request a tip from their users? Could it be a way to incentivize more generous contributions, or perhaps it's a way for them to cover operational costs? Does the tip go directly to the creators of the campaigns, or does it remain with Indiegogo? And, how does this tipping system compare to other crowdfunding platforms? Are there any potential drawbacks to this approach, such as creating an imbalance in funding opportunities for certain types of projects? It's certainly an interesting aspect of the crowdfunding process, and one that deserves further examination.