I usually DO show up at parties empty handed (unless we are talking about showers or graduation parties and the like). I ask the host or hostess if I could bring anything and if the answer is "No, we have everything covered," then I don't run out and buy a gift. And usually the answer is no but if it isn't then of course I'm happy to bring something. If I'm having the party, I decline offers.
My friends have everything they need. They don't want gifts. Neither do I. I'd like to get rid of some of the stuff I've accumulated over the years! In fact I I've been making a trek to Goodwill every week now for months.
And everyone is busy. It just adds to someone's stress if they have to be thinking, Oh Saturday is Lynn's dinner party and I need to find time to go get her a hostess gift. I just want them to come and relax and have a great time. Every social occasion does not need to be a gift giving occasion.
I guess we have different ideas of A) what proper visiting behavior is and B) what constitutes a gift.
I don't consider showing up to a party with [depending on type of gathering] a bouquet of flowers, case of beer or bottle of wine/spirits to even be a gift. It's simply what I was brought up to do - never show up empty handed. Ok at a very casual "hey you want to come over for dinner?" that isn't a party I might be more lax, but this was an established party.
And it all goes back to the conversational type invite - who doesn't ask "oh can I bring anything?" even you are saying you do show up empty handed but at least you "ask the host or hostess if [you] could bring anything" - seems like this OP didn't even do that - if she had she'd have gottent eh conversation about party details rolling.