That means all the the CP, hate speech — and in this case, piracy — that are posted on Reddit are Reddit’s responsibility.
Of course not, from reddit’s ToS: "By submitting Your Content to the Services, you represent and warrant that you have all rights, power, and authority necessary to grant the rights to Your Content contained within these Terms. Because you alone are responsible for Your Content, you may expose yourself to liability if you post or share Content without all necessary rights.
You retain any ownership rights you have in Your Content, but you grant Reddit the following license to use that Content:
When Your Content is created with or submitted to the Services, you grant us a worldwide, royalty-free, perpetual, irrevocable, non-exclusive, transferable, and sublicensable license to use, copy, modify, adapt, prepare derivative works of, distribute, store, perform, and display Your Content and any name, username, voice, or likeness provided in connection with Your Content in all media formats and channels now known or later developed anywhere in the world. This license includes the right for us to make Your Content available for syndication, broadcast, distribution, or publication by other companies, organizations, or individuals who partner with Reddit. You also agree that we may remove metadata associated with Your Content, and you irrevocably waive any claims and assertions of moral rights or attribution with respect to Your Content." –https://www.redditinc.com/policies/user-agreement-september-12-2021
Reddit reserves all the rights to everything you post ("When Your Content is created with or submitted to the Services, you grant us a worldwide, royalty-free, perpetual, irrevocable, non-exclusive, transferable, etc., etc.), but you alone are responsible for it (“Because you alone are responsible for Your Content, you may expose yourself to liability if you post or share Content without all necessary rights.”).