Do you think they focus on how many "G" you pull in the crash or how many drinks you had??
An NTSB report should not focus on anything, but should list and analyze all the possible circumstances that may have anything to do with the accident.
If ever this results in a court case/insurance claim or whatever, then it's up to a judge, jury, claims adjuster or somebody like that, to decide which factor(s) was/were to blame.