Everyone knows that the way to improve at chess is to solve tactics puzzles.  But why do tactics books make amateurs study grandmaster or master games? How useful is it to analyze games that are unreal for everyday chess players?
In the real world of beginning and casual players openings are dubious, positions are messy, material is uneven, and cheap traps and oversights are occurring constantly. Most amateur games are won by rather primitive means, compared to the cool and fancy moves that masters need in order to gain victory.
This book only takes positions from amateur games and puts them out there, warts and all. Tim Brennan and Andrea  Carson have assembled thousands of games by everyday players, and selected the most instructive tactical examples.
If you have limited time and energy to devote to chess, you want to study positions that are happening in games you yourself might have played!