Some houses are more popular than others.
There are times when I’m interested in a house that has attracted a huge amount of attention and bids. You know the house is going to go for WAY over asking. Before I submit an offer, I ask my realtor if they can find out if my offer of 40-50k over asking is going to be competitive. What do the sellers have to gain by refusing to answer? If there are offers 100k over asking with everything waived; I’m completely out of the running, their potential response is not giving me any information that will affect my bid amount. It just means more work for both of us.