YouTube's protection from legal action for copyright infringement isn't an automatic thing under copyright law. The Digital Millennium Copyright Act of 1998 specifically created a "safe harbor" exemption for platforms like YouTube that might inadvertently host infringing content. It placed the burden for identifying infringement on the rights holder through a formal notice to the website.
Websites like Kickstarter and Indiegogo can also claim "safe harbor" protection for any infringing material that appears on their platforms. Their terms of service place the onus on the people seeking funding for ensuring they have secured the rights to produce/distribute whatever products are part of the projects' proposals. However, I don't believe safe harbor would apply in instances where the platform knowingly engages with projects — as Indiegogo did in its recruitment of Axanar —that make it crystal clear in their proposal they do not have a license from the relevant copyright holders.
Yes, IGG is considerably more problematic.