Questions like why is something or someone not well known are not well posed mathematical questions, and are therefore likely to be closed as primarily opinion-based. If you can modify such a question to something like "Why is this appealing method not useful?", it might be more welcome; just make sure that the question is actually a question, not an start of a discussion and it's probably fine. These pages at our help pages give a good idea of what kinds of questions work here.
There are many textbooks out there, and not all of them are well known. Therefore I would find it more reasonable to ask why some book is well known, but such questions also have the restrictions mentioned above.
I don't know the book you were planning to ask about, but it seems to claim too much. The description makes the book sound like a full treatment of nonlinear algebra, which is certainly not possible. It may be useful to some and contain clever ideas, but the description you cite claims too much. A book need not be wonderful even if its cover claims so – reliable evidence for greatness can only be something external to the book. (And this applies to all books, not just mathematical ones.)