You're missing a lot of nuance. Graebers work is great. Tons of evidence-based discussions and thorough logic. What you've written here is even really deserving of a forum post.
Yeah but that chain of comments was originally talking about James C. Scott "against the grain". A historian specialized in early agricultural history and thus relevant here in that comment section about early human history.
I even got confused and thought that Scott wrote "bullshit job", but it's Graeber.
In regards to jobs: I think it's perfectly conceivable that one job is useful to a few, but generally pointless for society.
"He was an anarchist from the age of 16, according to an interview he gave to The Village Voice in 2005."
https://en.wikipedia.org/wiki/David_Graeber