Just my two cents.
Many people REFUSE to feed anything close to a species appropriate diet. The number one excuse (that I hear) is "I can't afford..." In reality they don't WANT to afford. They don't want to be inconvenienced in the slightest. They don't want to change their routine. They don't want to be educated. They don't want to know the damage they are doing to their pets. They don't want to be know that their pets are only surviving, not thriving. Oh, but they LOVE their pets SO much. Grrr
By choosing the words, "If all you can afford," Karen Becker is keeping the lines of communication open with those people. By not slamming the door shut, those people will hear EVERYTHING else she has to say about species appropriate diets. AND she has a lot of friends and acquaintances that are educating people about species appropriate diets. Eventually, the info will sink in for some. Some is better then none.