Witness requirements on recording documents is often due to recording laws. FL, for example, requires two witnesses on deeds that convey property. Witnesses are not required on mortgages, since there is no transfer of ownership. IN FL, a notary can act as a witness to most documents requiring witnesses (with certain restrictions). More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.