Why is at home hair color a no no?

It could be that I'm a stylist, and therefor have a bias to home hair coloring. However I have many reasons why I dislike the way at home hair color looks, treats your precious hair, and disables your hairdresser. Very often muddy and dull colors result, uneven and blotchy color give away your dirty little secret. There is no comparison as to how salon color shines, has depth and the silky and soft result you can only receive at a salon. Another reason at home hair color can be disastrous is that many do not know enough about hair color to begin with. Different levels of lightness are only perceived through what the color on the box looks like, meaning, for example, that dark blonde in your mind is different than what the box means. Also, tone is completely different than the level of lightness, the words these companies use for tones would be for example black can turn black blue certain tones can turn much warmer or cooler than expected, in short the results are extremely unpredictable. Different hair types color differently (thin, medium, thick and grey) this will effect how well the color takes, how light you can get your hair and how long it will stay. Hot roots can also happen (brighter/lighter and all around different color results from your outgrowth) this happens if the color isn’t matched well, or when the unpredictable happens. At home hair color also uses much stronger chemicals than you need on your hair, especially if your hair is previously colored this can cause damaged ends, these boxes can also be misleading about the damage they can cause. In short at home hair color is deceiving, unpredictable and damaging. In the end if your hair is messed up by your at home experiment you’re bound to spend much much more time and money correcting it with a professional, who will always know what is best for your hair in the first place.
I supposed I’ll write a more technical explanation in the near future, but for now keep this in mind when your impatient at home for a change.