0. There's no singular leftist philosophy in a world where anarchists and socialists and moderates and centrists are all ostensibly on the same side, but there are points of agreement (nazis are bad, every human being deserves equal dignity, people should have agency over their own bodies except where that agency meaningfully harms others, etc). When I refer to leftist thought I'm trying to refer to my understanding of that overlap. Also I'll number by paragraph I'm responding to.
1. To your first paragraph I'd say that's not the usual argument that I've heard from people on the left. I mean there are kooky people out there, but I think most people would say having privilege doesn't make you inherently immoral, nor is lacking power inherently moral. Morality is based on choices, with the understanding that choosing not to act is still seen as a choice.
Having systemic power gives you a greater capacity to affect change. I do think some people will see refusing to act appropriately to change things for the better when it's easier because you have power as more immoral than if you refuse to act when you lack systemic power, so in that sense you are right, but that's only true if you don't act.
Further I just don't think guilt is really the focus for most people on the left, except to understand how we got to the current status quo; What's more important is people taking responsibility and acting, and attempting to share power so that others can also act.
2. There are certainly people who intentionally work to maintain and expand their power; wealthy people who push for lower tax rates on the wealthy come to mind. Still, a large part of feminist and anti-racist theory seems to be about creating knowledge of privilege in people who take it for granted, and then pointing out the responsibility that suggests. There are conspiracy minded folks to be sure, but I don't know that that jibes with the idea of invisible privilege. I suppose you could argue it doesn't and suggest leftist philosophy isn't perfectly coherent or in agreement though. I'll have to think about this.
3. There's a whole thing in leftist philosophy about how intent is not the same thing as impact. It doesn't matter if systems that perpetuate injustice were built for the best of intentions or the worst or are just weird historical artifacts like the electoral college, what matters is the harm done, and how it falls disproportionately on members of marginalized groups. Thus the whole emphasis on anti-racism instead of not being racist, since merely not acting to further racism doesn't mitigate the harm that exists currently, and is thus also immoral. If that's confusing, look up Good Germans.
4. I'm not sure I understood why you were saying this, but to the extent that I understood I think I agree with you that not every relationship with power is affected. I see a meaningful difference in situations where a person has significant institutional or structural power vs situations where the power comes with the approval of those over whom power is wielded directly.
5.A cute trick? So does that mean you are suggesting that racism was not historically a term mainly used to describe the Nazis and other white supremacists, and sexism a term mainly used to describe the gender inequality that women faced?
I would argue that your original definition is in fact a conservative redefinition, one that treats an unequal status quo as an entitlement of those with power by pretending they are the true victims because people are attempting to redress social injustices.
I guess in the post modern sense any viewpoint can be correct because everything is subjective and based on one's viewpoint, but I'm not a post modernist and to me that seems like BS. I think terms are regularly redefined by people on the right in order to muddy the water and generate fear.
I guess I can say, at least we agree the water is muddy?
This has been fun, not sure I'll respond more or not in this thread but you've given me some food for thought.