Single-issue advocacy groups have gone out of fashion. That's a problem for the left.
You're wrong about Israel, but we can set that aside. You're right about focus, but it's hard to escape the impression that effectiveness isn't the real goal in the first place, but rather to "make the progressive operatives who run these organizations feel good".
"Intersectionality" is increasingly understood to mean there is one right opinion about everything and to be a Good Person one must not only hold but espouse it. Because silence is violence, after all. We wouldn't want to be violent individuals, would we? Or, even worse, heretics. Just as 15th century Catholicism had no a la carte menu, neither does 21st century Wokeness.
Yes, if you think about it in terms of Venn diagrams, multi-issue organizations only appeal to the people who are at the intersection of all the issues. This is always a smaller number than the original set. Admittedly, there is more alignment among liberals than there used to be, but it still is limiting. Just yesterday, the ACLU came out in favor of forgiving student debt. What has that to do with civil liberties?
Good article. I would also emphasize the extent to which left-liberal ideology is the result of historic coincidence. Research shows that it is more common for right-wing cultural views to be coupled with left-wing economic views. A study of 99 countries found that this was the case, particularly among poorer citizens (Malka et al., 2017). The left-liberalism of Western elites has some coherence, reflecting the preference of sociocultural professionals for equality and solidarity, but is also a result of the alliances of workers and liberals which crystallized in the 19th century. In Central and Eastern European (CEE) countries, such conditions were absent and left-liberal movements failed to emerge. And this doesn't begin to address issues like Israel/the environment/transgender rights, which are very eclectic.
So aside from the tactical issues, intersectionality has a very weak intellectual basis.