Businesses with neither viral effects nor network effects tend to produce linear, straight-line growth. Linear growth can produce a business, but not the kind of high impact, exciting growth we're all looking for. We all want the green-line growth curve.
Founders should push themselves and their teams to reach geometric growth, and be able to measure and know the difference when you've crossed from linear to geometric growth. Network effect businesses, once they hit the tipping point, typically show this type of geometric growth, either because a) they are viral, or b) their metrics are so good, they can afford to buy the traffic vs other competitors.