It doesn’t surprise me that Sherman created his own propaganda in the field. Sherman hated journalists. Didn’t trust any of them, and didn’t want them anywhere near his campaigns. If they came to camp, he threw them out. He believed they undermined the Union Army’s efforts to win the war, basically helping the enemy with the information they published. Looks like he spun his own war disinformation to the public just like the drive-by media does today.
Im reading Jeff Shaara’s book on the Battle for Vicksburg. I am a Civil War buff, but not as well read as some others (maybe 40-50 books). This is my first significant exposure to Sherman. I think Jeff Shaara would agree with you completely.