This kind of thing certainly make it harder to sell memoir, but for authors > publishers and to the public.
But what should a publisher do?
Book publishers do not engage in systematic fact checking. On the face of it, how would you know a story like this is false? Many of these memoirs (this one, the Frey book, the Holocaust tale) come from people who flew under the radar, with no real online presence. So checking is not quick and easy.
Let me offer two examples from my own life . . .
The key points of Look Me in the Eye (where I lived, my friends, my careers) are all verifiable in five minutes online, because I did things that others wrote about. But what if I'd done sound for a local band, instead of played with KISS? What if I'd been a manager at the local Cadillac dealer instead of starting Robison Service? Just a few steps down and I'd have been invisible . . .
Which takes us to where my brother was. As a kid, he didn't do anything you could read about online. How do you know if his claims about the doctor in RWS were true? Well, as it happened, the doctors kids challenged his claims in a very public way, and St Martins responded with a defense. Several years later, my brother prevailed. After lawyers from both sides interviewed the surviving players, and read all the printed material extant, the book stood unchanged.
Do you have any idea what that fact checking via attorneys cost?
Upwards of half a million dollars.
What should a publisher do?
In my experience hanging around Crown, they don't have a big surplus of people. Who would do it at a typical publisher? And how? It's somewhat easy to see if a person attended a particular school, but what about checking on friends/enemies/people in the tale? It's hard to see how they'd do it all.
I also think such a fact checking operation might stifle creativity, if authors had to justify themselves line by line.
That said, publishers are aware of the need to print stuff that's correct. However, most trust authors to be partners in pursuit of this goal. We have questions of who said what, but it's up to me to get those answers. If the authors can't be trusted, the whole system sort of falls apart.