I think the idea is that they're invisible in the sense that nobody announces them to the general public. Moral challenges to the status quo used to be communicated explicitly by heads of reform movements or revolutionary struggles. You had anti-slavery leaders, anti-Satanist leaders, feminist leaders, AIDS epidemic leaders and so on. Now the moral changes are spread online memetically and are implicitly adopted by people along the tried-and-true liberal-vs-conservative lines (usually with a minimal level of understanding), and then power structures start to implement them as rules to look good to what they perceive is their important audience.