I concede your points, but people who don't want to be photographed at an event which of its very nature is much photographed, just need to be aware of that and stay out of range of the viewfinder. That is not a Herculean task.
I agree with this. Then there is this interpretation (which is new to me) that individuals who expressly consent to be photographed in groups at Wikimedia events can also expect their photos not be published online on either Commons or social media (without explaining their position to photographers). I don't think this ever used to be the case. Wikimania, by its very nature, is a social event and there was always a presumption of consent in the absence of express prohibition.
I do think now that there is a need for FSP to explicate norms for photography and publishing.