Must the sponsor of skilled immigrants in Australia be a relative?

Skilled immigrants in Australia can be divided into two categories: ordinary skilled immigrants and sponsored skilled immigrants (887 categories). Generally, skilled immigrants do not need a guarantor, while guaranteed skilled immigrants are guaranteed by the applicant's close relatives or the state government. If the next of kin is the guarantor, the guarantor must live in a remote area for more than two years. They guarantee that the applicants will live and work in remote areas after emigration, and the passing score of the applicants will be reduced to 100. Friends are not allowed to act as guarantors.