Like others, I think some books get out of date and become dangerous to the beginner because a beginner does not have the knowledge base to understand which concepts have gone down in value and which new concepts have become more significant.
for example...
Old online cash books were written before Fast Poker (Zoom etc) were deployed. Anybody that plays Fast Poker knows that population tendencies are far, far more important than individual tendencies because the vast majority of the time you will be in read-less spots (and it's not even close). Concepts like Bayes Theorem, which is a timeless math based theorem, rises in significance because the Fast Poker player is constantly looking for the slightest hint of info to add to the population reads.
Much of what is written in old cash books is fundamentally "how to play exploitive poker against a specific villain". In Fast Poker, much of the time you will either playing "GTO style" (not my "expression" and I hate it but w/e) or trying to exploit the population, not the individual, and that applies all the way down to 5nlz where many beginners start out.
In order for the beginner to get anywhere in this environment, they have to start constructing ranges, balancing ranges, as well as applying basics like ABC poker.
A modern book like The Grinders Manual will teach you all this stuff from the get go. An old book like Harrington on 6 Max will not (and I doubt Harrington gets most of it anyway, he's probably never played Zoom in his life
)
Of course that's just one example... there are loads of different structures and playing environments and and oldish books for example again, Professional No Limit Holdem with all it's SPR stuff, will still have validity in live environments were very little evolves and it will always be about exploiting fish. But the online beginner who picks up this 2007 book and reads it expecting it will serve them well online is heading for a world of pain.
tl/dr If you are starting out in the modern game and books are your thing...buy the most modern (well-reviewed ones) run a mile from the old stuff.