Thats now how history works at all man. Pretty much all writing on history goes into the metaphorical dust bin maybe 20-40 years after it is created but the "dust bin" isn't a dead place that no one should ever explore, its the world of historiography, and understanding how people understood their point in time at different points in time. No one should read a history book like its the bible handed down from on high, they should read it knowing the authors biases, the contemporary views on the authors work from other experts in the field, and an understanding of their own knowledge level and context. The reality is that a huge amount of K-12 American history education is propaganda and for someone with a K-12 American history background this book is a very compelling read that provides a useful counter narrative to what they have been taught, the main function of which is not to blindly trust the words in the book, but to understand the practice of history not as a recitation of facts but an analysis of past events with a specific point of view, and how different points of view from authors with different motivations can give different views of the past. IMO, this really brought the field of history to life for me.
GP may have phrased it a bit dismissively but I read that comment as making the same argument you do: no given history book contains the final truth.
As for GP's comment that Zinn has no place today -- you offer a more nuanced take. But we're in a moment replete with valorizing paeans to Zinn (like TFA) and calls for using People's History more widely as a _textbook_. Maybe, given that we are 40 years on from it's writing, that's not the best move.
At no point have I seen anyone point out a factual error that Zinn has made, only that people don't like the conclusions he draws from those facts. Another commonly repeated point is that there are other historical works that do a better job than A People's History. That is almost certainly true as well, but that claim is no more relevant than pointing out that there are better scientific works that do a better job than Einstein's "Relativity: The Special and General Theory".
Having read A People's History, the very beginning of the book explicitly states that he is biased, that bias is something very hard to escape in almost any social study and is present among almost all historical literature whether the author admits it or not, and that the difference between his book and other historical works is that he makes the conscious decision to be biased from the point of view of the people who were conquered as opposed to writing from the point of view of the people who did the conquering.
Certainly Zinn has likely made some errors, but none of them are in the link you provided (as far as I could tell).
This is not the limit of criticism of history scholarship. Braudel's Civilization and Capitalism isn't considered dated because of factual errors but instead because it over-represents a particular narrative and analysis style that fails to paint a detailed picture of things.
History scholarship is absolutely not a list of facts. It is the construction of a narrative from source material. A text that is 100% truthful to fact can still be entirely bogus scholarship (I'm not saying that Zinn's is).
I happen to disagree with a lot of his political opinions but I think it's very important that APHUS exists.
Come to think about of it actually, it's also similar with the criticism of David Graeber's (RIP) book "Debt", which usually focus on "well, he wrote something really wrong paragraph about Apple, so you can't believe anything he writes really"
Zinn decided to bias the viewpoint towards oppressed people, the same way many textbooks bias it in favor of the 'winning' party. While I felt like I got a pretty decent education in high school history, Zinn didn't invalidate what I learned but showed quite clearly how these things affected others.
When I was in school it would have been highly controversial to compare chattel slavery or the conquering of the New World to the holocaust but the reality is the severity is similar, just on a different timeframe.