It depends what type of aircraft you are flying.
When people talk about this, it is usually specifically in relation to the final approach.
In light aircraft, such as a C172, it is common to be taught to maintain your airspeed using pitch, which isn't hard to do... if you pitch up, you lose speed, and if you pitch down, you increase speed.
If you pitch for speed, then adding power naturally makes you climb (or decrease your rate of descent), or reducing power makes you descend (or increase your rate of descent)... so in this respect the textbook is correct... it is certainly how I (along with 90% of students in Australia) were taught to fly.
This works fine in a light aircraft, however isn't particulally effective in a large one. A jet is usually flown so that pitch is rate of descent and thrust is speed, which as you point out is a little more intuitive.
Note you can use the second method on a light aircraft usually quite successfully.