When there are multi offers you written a clean offer asking for very little. No warranty, no termite report/repairs, no wish list, short contingency removal, no closing cost ............ nothing. That is not to say you shouldn't suggest to your buyer to perform inspections, just don't make them part of the contractual obligation for the seller to perform. You want to write a clean contract that yells "pick me" when the seller is going through the pile of offers.
When a seller (not a foreclosure) is selling and they are moving out of area it is often a good suggestion to have them off to pay half of the warranty as an incentive for the buyer to purchase. This is good "peace of mind" insurance as you will nor be around to deal with problems that may arise after the sale.
I've personally never purchased a home warranty as a listing agent. This is why there are disclosures suggesting buyer get inspections and to give them advisories to sign and return. Once you point the buyer to satisfy themselves by written disclosure your libabily has decreased substantially unless you are involved in some sort of fraud by not disclosing known facts.
I always tell a seller to disclose as much facts as they have in regards to known conditions. More disclosure equals less liability.
A home warranty policy costs around $400-500 (SFR). It is normal to ask the seller to pay for the policy unless your are purchasing a distressed (short sale or REO) where the seller is not willing to provide. In that case either you don't get one, the buyer pays or the agent pays. I have provided one for clients in a distressed propery situation but I don't know if it is the norm.
I am not a lawyer, but liability can be spread among many of the people involved in a sale, not just the broker. If the home inspector missed something important, he or she could be sued. The agent who doesn't perform an Agent's Visual Inspection Disclosure (or does it poorly) could be liable for missing something serious. And so on. A home warranty is an inexpensive form of insurance against all kinds of issues, not just broker liability.