Out of context, that opening line is a little jarring. Ultimately, using the broadest definitions of culture (and of course later recognizing her limits and failures in relation to gender and sex), bell hooks is arguing the impracticality of complete separation of men and women, boys and girls, and any other combination of relations in modern US culture. While adults do have a real opportunity to seek those separate spaces, most people won’t choose this course and plenty simply can’t, especially children and also men and women in heterosexual relationships or wish to pursue those.
The argumentative thrust of the whole, though, aside from these potential limitations is a breakdown of the different ways in which patriarchy fails men, even if men are also the most rewarded of people within patriarchy. Her argument, demonstrated across multiple social strata and contexts, is that patriarchy leaves men broken and incomplete, unable to have, process, or deal with complex emotions outside of anger and fear, and places them in a position to wreak havoc on those other people in their lives, and that this process starts early in childhood, and requires care and love and guidance to break the cycle.
Ultimately this book isn’t for everybody, in the sense that it might not be particularly helpful to someone sort of “advanced” in the conversation, except that it does provide some real clarity on the issues. But for a lot of people, this provided a compassionate, clear, detailed, and articulated entry point into understanding patriarchy, via its effects on men in particular. It has limits in that it’s an introductory text, that it does not spend enough time dealing with Queer identities, and completely ignores trans men.