Every nonfiction book written by someone that's on the staff of a publication is exactly like this, unless it's simply an anthology.
Woodward still works for the Post yet has three books about every presidency with new info; Jane Mayer's books about the Kochs and secret torture programs had info that was held from The New Yorker and would have been useful being revealed earlier; Ronan Farrow's Catch and Kill same thing; NY Times' Jodi Kantor and Megan Twohey's MeToo book; Stelter's new book on Fox News has stuff about their relationship with Trump he's never given to CNN; Joshua Green's book on Bannon had stuff he didn't give Bloomberg; Philip Rucker and Carol Leonnig's A Very Stable Genius had stuff they didn't give Washington Post.
And on and on and on. And that's just from the past few years; it's been going on with every major issue and every president for a long time. If every book written by someone on staff is a disservice to the public (and they might be!), I don't see why Schmidt should be singled out. I personally don't have a problem with his or any book like it, but as the spouse of a literary agent who makes money on people saving this stuff for their books...I am a bit biased.