It can be a definite plus, especially when the seller is including a home warranty in with the sale of their home.
Home warranties are best when the age of furnaces, A/C units, water heaters and appliances are unknown. As they can be expensive repairs, it can offer 'peace of mind' to home buyers.
But not all warranties are alike. So you need to know what the warranty covers and how much is the cost of deductible per incident. You may discover that the cost is not worth what the warranty covers.