I have to politely disagree. Most home growers that I know of recieve one rhizome when they order one and that's what they plant.
Most home growers have that one rhizome grow into an established plant. I have 12 plants of nine different varieties all purchased from freshops single rhizomes over the last several years.
Over the last few years as a member here I have only encountered a few posts of home growers planting multiple rhizomes. The only reason I can think of is that home growers give much more care to their small number of plants so a single rhizome has a much better chance of taking off than if it was one of 10000. It's what we do
Most farmers throw more than one rhizome in because it's more cost-effective than checking each row of hills for growth.