Answer:
Because it destroys healthy skin cells.
Step-by-step explanation:
Hydrogen peroxide is an antiseptic that is more potent than 70% isopropyl alcohol and betadine but even then it is not used by doctors because it has a damaging effect on skin cells.
Our cells contain catalase enzyme which reacts with hydrogen peroxide and release reactive oxygen species which cause cytotoxic effect. So applying hydrogen peroxide on the wound to clean it destroys the cells and delay the healing of the wound.
Therefore due to damaging side effects of hydrogen peroxide on human cells, it is generally not used by doctors.