Why is HR Management Important to all Managers?

Why is HR Management Important to all Managers?
It is important to avoid following mistakes

1. Hire the wrong person
2. Experience high turnover
3. Have your people not doing their best
4. Waste time with useless interviews
5. Have your company taken to court because of
discriminatory actions
6-Have your company cited under federal occupational safety laws for unsafe practices
7.Have some employees think that their salaries are unfair and inequitable relative to other organizations
8.Allow a lack of training to undermine your department’s effectiveness
9.Commit any unfair labor practices.