Message amplification isn't linear
Put two loudspeakers next to each other, and the perceived sound isn't twice as loud--and ten times as many speakers certainly doesn't seem ten times as loud.
But when you hear an idea from two people, it counts for twice as much as if you randomly hear it once. And if you hear an idea from ten people, the impact is completely off the charts compared to just one person whispering in your ear.
Coordinating and amplifying the evangelists of your idea is a big part of the secret of marketing with impact.