The thing I find with books from the library and bookstores etc is a lot of them aren't written in New Zealand and a lot of the fish species in them you cannot even get here! The water is different here, the temperatures are different,  Which can be confusing for newbies. 
 
I agree also that most books contradict themselves with others. 
Just like the forums. But you cannot 'probe' the book for more information or ask the book to detail something a little more if you don't understand. 
What works for one person - many not work with someone else. 
 
I'm particularly fond of native fish (which apart from a few members on here) there are absolutely NO resources out there for keeping them. 
 
Personally I think its great to have a wide range of opinions!!