The plant is easy to maintain and propagate. Almost any soil will do. And it is easy to make rooted cuttings. The polyscias are such excellent house plants that others hardly compare. The answer has to do with the way plants of this genus, like some other house plants, have been prepared for market.
House plants can vary greatly, depending on their source.
Their differences are partly due to parentage, but even more to methods of culture. In the process by which an exotic species is brought into commerce, initial improvements in breeding and culture make it popular with a broad segment of the indoor grower and landscaper market. At first only one or a few nurseries produce the successful plant. But soon others see an opportunity to share in the profits. That is most frequently accomplished by speeding growth.