I say soil testing is not necessary for the family gardener because our experience  has indicated such to be the case as we have grown gardens and assisted people around the world.  In Jacob Mittleider's early books he did advocate soil tests, but after many years of experience he removed those statements from his later books.
The reasons he did this included 1) one big reason for soil tests is to determine the pH, and his experience taught him that he (and every one of us) could determine what we needed to know about pH by finding out the amount of annual rainfall.  Everywhere annual rainfall is more than 20" the soil pH will be acidic (below 7), and wherever annual rainfall is below 18" the soil is alkaline (pH above 7).
And the solution to getting pH into the ideal range for plant growth is to provide calcium (an essential plant nutrient, and "the foundation of a good feeding program") in the form of lime whenever rainfall is above 20", and in the form of gypsum wherever rainfall is below 20".   The application of calcium is done separately from the regular weekly feeding regimen.  We apply what's called a Pre-Plant Mix before planting of every crop, and for crops that will be growing longer than 3 months we apply Pre-Plant a second time (and even a third time if necessary).  All of this information is explained in The Mittleider Gardening course book - www.growfood.com/shop
2)  The second reason for soil testing is to determine the levels of nutrition of the numerous essential elements in the soil.  Again, Dr. Mittleider's vast experience taught him over the years that almost always the AVAILABLE nutrition is deficient for most all of the elements, and so the best use of peoples' time and money is to assume the nutrients are needed and feed all plants a complete and balanced diet throughout the growing season.  This is called the Weekly Feed mix, and once again is explained in The Mittleider gardening Course book.