Sellers will heavily favor a cash offer, as it's faster and far more assured of going through. One strategy I've heard about people doing is to take a pile of cash, acquire the property, and then refinance it pulling out 80% of what they put in so that they can both have a mortgage and have a stronger buying position. Add in things like dropping inspection, no contingencies, etc... and it gets really hard for many first time home buyers to compete.
Additionally, coming in with an FHA 3.5% down, vs someone with a traditional 20% down - the sellers will favor the 20% as again it's less paperwork, easier, faster, and more certain to go through if the assessment is off by a few %.
I had no idea about this before trying to buy a property in New England. So much of traditional advice doesn't include these details.
What's weird about it to me is that this is one of the few places in US consumer markets where the seller cares deeply about your method of purchase and where the money came from. Buying a used car? They don't care if it's cash, credit, loan, etc generally. Hell, most car dealers want you to use a loan from them and would prefer that over cash in many ways. When you go to WalMart, they don't deny you buying something for using a credit card vs cash.