I don't think it matters that a third of the pages are spent on parsing - that only covers 20% of the chapters. It's just that parsing takes somewhat more space to explain because the figures, tables, and examples take up relatively more space than when explaining e.g. type checking. I think it is a superficial knee-jerk reaction to classify this book as mostly being about parsing.

Also, while it is true that production compilers (especially optimising ones) have relatively little effort spent on their parsers compared to everything else, if you consider a bare minimum compiler, parsing is going to be a proportionally much larger part of it - especially if you do not use a prewritten parser generator (which this book assumes you do not, since it's partly about how you would create such a generator).

I definitely agree that too many compiler resources place too much emphasis on parsing, but I don't think this specific book is a particularly egregious case. I have also read Appel's books, and while they are good, I think you need to have read something else first to cover the basics.