So you're going to assign some arbitrary threshold whereby it's okay for you to judge a whole group of people based on the behaviour of some. Majority of people in Africa are probably anti-gay so is it okay to say 'f**k Africans'? Anyway, whether it's few, some or many it's not all. What about all the straight people that are going out of their way to help as I pointed out?
Even if you want to stick to this idea that somehow all straight people are guilty because a certain sub-set of them are, where do you think that will get you?
In an equal world - of course it's not ok to do this, and no, I understand and agree that comments such as 'fuck <group>' are never constructive or helpful. But I don't think that's the point.
It's been said before, there's no power in 'fuck straight people'. Straight people aren't hurt by that, their power isn't taken away, their place in society isn't diminished and as for the many straight allies - if they're truly allies they should understand our anger and be able to separate themselves from the comments.
To draw a comparison - my tumblr dash is often filled to the brim with the latest injustice to black people. Whether it's some cop shooting somebody for literally no reason, or an 'all lives matter' protest - every time stuff like that happens I see an onslaught of anger towards white people.
When somebody posts this stuff, with tags like 'fuck white people' or 'white people are the worst' - genuinely, being white myself, I fucking agree. I can't deny what's happening in the world, the white people that act this way are trash and I hate that they make other races feel like this. I understand the anger, don't feel offended by it and hope that during the course of my life I can contribute towards positive change. Because that's the only way things will change for poc, and other oppressed minorities. The people with the power, the straights, the whites, the men, they need to recognise the wrongs and use their fucking privilege to influence positive change.
^^ horribly articulated but hopefully you see my point.