Phonetic components usually also convey pictorial or semantic information.

 phonetic components in pictophonetic characters are not purely arbitrary.  The six methods are not mutually exclusive, instead they are mutually reinforcing. There are dozens, usually hundreds of potential phonetic components. They were not chosen arbitrarily, they may also depict imagery or meaning. Your mom is like a horse, 妈　because she works very hard. A number 码　is like a horse, for we keep count of horses, notably the number of statues of horses buried with the emperor. You may often scold your horse　骂. You can do this for most all characters.　吗

The six methods were described AFTER the formation of most Chinese characters. They are mutually reinforcing, not exclusive.