It seems so obviously counterproductive that the only thing I can think is that they’re enjoying it, like it’s a kink to get into other people’s sex lives and tell them what they should and should not do.

No, seriously. If you spend time in the conservative, christian communities like where I grew up, you hear these people just spend night and fucking day thinking about “sin” and the ways that nasty, dirty, eeeeevil sinners like to sin and all the details about what manner of sin they partake in… and so on.