Would you agree that we can conclude that the incidence of burnout is high amongst software developers? The "real" level may be 83% or 93% or 43% but it seems fair to conclude that it is indeed some larger than desirable number that merits a larger and more robust study.

That is the value of a study of this size. The ability to quickly determine if there is any "there" there. The headline is sensationalistic but such is the nature of publish or perish science today.