The name given to postiions of power and authority like chariman and policeman often emphasize the male gender. why does this matter?

According to the question's description, any job that prefers a particular gendered person suitable for that position is signified with a particular name. For example any male is considered suitable for a job that is regarded with the chairman, watchman etc.

Names that are specifically given to a job's designation defines about that particular male or female is the best suited to perform the particular work and responsibility as compared with the other gender.