Ideally, any legal document transferring ownership should be created by the person receiving the property (assignee’s lawyer) and then reviewed and signed by the person selling it (assignor or vendor). You need to protect the interest of the new owner.
However, for estate properties, since they already have a standard legal document the seller/ vendor’s lawyer usually prepares the deed for the buyer’s lawyer to check.
Unlike tenancy agreement where the owner still retains ownership and needs to protect vested interest. The agreement is prepared by landlord’s lawyer.