Also, rare chicken breast is apparently pretty unpleasant to eat. Kenji Lopez-Alt did an article where he discussed how you can use sous vide to pasteurize chicken while still keeping it at a low temp, but the result (while perfectly safe to eat) was not enjoyable.

"bacteria can travel to the surface of the muscles during the butchering process"

This way undersells what's actually happening: fecal matter from the intestines gets onto your meat. This shouldn't happen with proper practices.