One of his concluding statements:
They may have differed in some cases about which books were scriptural, but they agreed about many of them, as the texts illustrate. There was a sizable group of authoritative books, but not all Jews may have agreed on every work in that category, though there is too little evidence for deciding. (p. 71)Exactly right.
A couple of other points, though, I would want to question. First, I wonder why VanderKam thinks that the person who asked Jesus about the greatest command in Matthew 22 was a "Sadducean teacher" (p. 62). The Gospel writer clearly presents him as a Pharisee, not a Sadducee (22:34-35). It's not just a slip on VanderKam's part, because he proceeds to make a slight point out of his Sadducean identity. No big deal, though.
The other one is not a big deal either, and it is common enough to reason as VanderKam does:
[...] it would be difficult to argue that Chronicles, Esther, Ezra, and Nehemiah were significant at Qumran because there are very few copies of them and no other indication they were influential. (p. 67)This is very carefully worded, so, again, it's hard to disagree with it. But I wonder if "significance" is really the point we're after. If you ask the people I go to church with, "Is Nehemiah inspired by God, canonical, the eternal word of God for his people?" The answer would be "yes." But if you asked how Nehemiah is "significant" for that same church-goer, I fear you'd be greeted with a blank stare. The claims--or, if I may, the theory--are very lofty (Nehemiah is canonical scripture), but that doesn't lead people I go to church with to order their lives by Nehemiah, to quote it to prove doctrine, or even to read it very often. It's incredibly important (theoretically), but it's not really all that important (practically).
So, yes, I'd agree that the Qumran community gives little evidence of attributing "significance" to the four books named by VanderKam, but I'm not sure how far that takes us in terms of whether the Qumran community actually did consider (theoretically) those books significant or authoritative. My fellow church-goers don't give a whole lot of evidence of attributing much significance to those same books, but if you tried to tell them that those books were not canonical, you'd have a fight on your hands. (I'm in the Bible Belt, after all.) I'm not saying it would have been the same at Qumran, but I am saying that we don't know it wouldn't have been.