Capacity and scale are key. Ideally, we need to monitor registrations and use the information to effectively build relationships with delegates before events we can often/usually spot ‘freeloaders’ and reduce the impact.
One man bands can be significant influencers. An aspiring blogger who works in a niche market may only have an audience of 250 followers, but they may be the perfect end audience!
I guess it depends upon sector and if they are subject matter experts.