I think the first group is specific to PTSD... those are the reactions/symptoms that make PTSD what it is.
The others, as you say, are maybe more generalized reactions. You could have those reactions to traumatic events and not have the PTSD set. Or, as a lot of people have found, you can have both! (Oh, joy...)
I think the thing that appealed to me about it was to see some of the individual things I struggle with sort of "grouped" or organized. So that I can see that they're part of a pattern of behaviors. Somehow it makes me feel like less of a failure for struggling with these things. It's the power of naming.
Before I was diagnosed with PTSD, I just felt bad and crazy. Getting the group of symptoms named and identified as PTSD, something that other people struggle with, too, really helped. Seeing the shame characteristics was kind of the same feeling. Other people do this. Other people feel this. Other people react this way. I don't necessarily feel this way because I'm bad. And I'm not necessarily bad for struggling with these things.
Getting some of the guilt out of the way helps me feel like maybe I can work on the behaviors themselves better.