The shock result - voted for by 67% of the 300 attendees - was produced during a live digital survey at last month's gathering, which was produced by Revelation at Manchester Central.
Another worrying sign was that 78% believe they are not adequately resourced to manage major brands effectively at events.
Former NEC Group CEO Andrew Morris, who chaired this year's conference, said: "What we've heard at the conference is that it's all about content, content, content.
"Emotional engagement is a key strength of what we do. We must continue to improve the quality of our consumer experience and talk the brand language. We're an industry going through transformational growth."
The survey questions, managed by Crystal Interactive, were dotted between the day's guest speakers, who this year provided a distinctly multimedia theme.
The morning's presentations featured Patrick McKenna, founder of Ingenious Media, and Dave Allan of agency What If. Allan addressed the industry's need to believe its worth before alternative media can do the same. "The most important place perception needs to change is in your heads. If you believe that you're a mainstream media and start telling the world, then people will believe you," he said.
As part of his presentation, Allan pointed out the challenges of achieving cut-through for more traditional above-the-line media.
Before lunch the team dedicated a panel discussion to the late Factory Records founder Tony Wilson, who had been due to host a keynote session.
The afternoon began with a light-hearted Room 101 session hosted by Brand Events' Chris Hughes. This was followed by presentations from Howard Kosky, managing director of Markettiers4dc, Duncan Edwards, chief executive of the National Magazine Company, and Anthony Wreford, director at Omnicom Europe.
Kosky reported that in the past 10 years, ad effectiveness has fallen by 40%. He encouraged the event industry to embrace the internet rather than fear it. He said: "The industry should see it as a delivery mechanism, not a threat. It can complement events. I see conflict between exhibition organisers and exhibitors. There needs to be a joint objective."