That's a good point; the way I see it, the general social justice movement is largely a movement against hierarchy, and for valuing all people equally. It is naturally allied with feminism in the sense that both see the elimination of the gender gap as desirable.

I personally consider the SJ concepts destructive and anti-progressive: hierarchy can often be efficient, there is nothing fundamentally immoral about it, and since people's contributions to society are not equal, treating them equally is neither efficient nor just -- similarly to how treating them unequally based on superficial criteria such as gender is inefficient and unfair as well. But, we probably have a philosophical disagreement on this, which is really fine -- I wish the anti-efficiency and anti-growth people would stop calling themselves "progressives" though, but that's quite another topic...

I would have absolutely no problem with the feminism/SJ alliance, except for the empirical observation that when you hear someone proclaiming themselves as a feminist, most of the time it's a SJW in disguise, and then we have an unfortunate situation when a valid position is supported by entirely unacceptable arguments... Which is pretty much the reason I felt I had to comment on this, as I don't want people to consider the two concepts as identical.