Every "liberation" movement is designed with the intent of breaking down societal standards. It's just that it's very easy to pitch these things under the guise of "equality" without considering any of the ramifications.

As to why gays fall for it, the Left has done an amazing job promoting identity politics. It's appealing because it tells you you're owed something for existing. Lots of people fall for that. Gays are no different from women his with Women's Lib, and Blacks with BLM. If someone says "I'm going to give you free stuff that you're owed" it's hard to think critically past that to rationalize why it's nonsense.