isn’t the book mostly focusing on OD&D, then Lorraine should not show up at all. The Blumes certainly deserve some blame too, none of them (Gary and the Blumes) were any good at running an actual company
Depends which book you're talking about.
The one WotC published is
The Making of Original Dungeons & Dragons 1970-1977. It doesn't really talk about Gary's or the Blumes' virtues or flaws as people, businessmen, or designers. This is a big lavish coffee table reproduction of OD&D and its supplements (except the last one, Gods, Demigods & Heroes), a prepublication first draft of OD&D, as well as parts of Chainmail and a bunch of precursor and contemporary materials from when OD&D was being created and the years leading right up to that. Including correspondence between Gary and Dave, club newsletters and fanzines from their wargaming days including an issue of Thangorodrim which introduced dragon concepts later used in D&D, etc. This one has
almost no editorializing. It's mostly a 575 page loving reproduction and presentation of a bunch of historical materials in chronological order and factual description thereof. There are about a paragraph and a half of disclaimers / content warning in Jason Tondro's preface. Talking about a few problematic/unsavory elements in the reproduced texts, and not naming any names or denigrating any persons, living or dead. These have been mischaracterized by some misguided or genuinely delusional folks as attacking Gygax or other original creators or old-school fans. Jon Peterson, one of the primary researchers and compilers of the above volume, includes a few even milder words in his Foreword to the book as well. He also quotes two sentences of the legacy content disclaimer that WotC has on the old school TSR stuff on DM's Guild. These passages clarify that the writers and publishers aren't endorsing the instances of sexism in the text or making light of slavery; that this stuff is in there in a few places and the modern reader should be aware going in.
On the topic of the origins of D&D, Jon Peterson also wrote
Game Wizards: The Epic Battle for Dungeons & Dragons, a carefully-researched work on the origins and history of TSR as a business and the publishing of D&D, including the legal struggles between its various creators and stakeholders, up through Gary's ouster in 1985. This book does minimal editorializing. Peterson is a stickler for sourcing and backing up the things he writes in contemporaneous written documentation. He largely avoids making judgmental statements about anyone, usually preferring to let their own words and actions be judged by the reader. This one is from MIT Press.
The journalist Ben Riggs wrote an unrelated book,
Slaying the Dragon: A Secret History of Dungeons and Dragons, which is a pretty solid history of D&D as well, and overlaps with Peterson's history and documents much of the same stuff (albeit in less detail) from the early 70s to '85, but differs in extending his coverage through the Lorraine Williams years until and for a bit after WotC's acquisition of TSR. As well as in relying more on supplementary personal verbal accounts and interviews with some of the people involved many years after the fact. This one is from St. Martin's Press.