“Almost as many” means “not quite as many.” This simply reinforces the ad’s premise: Omnicide kills the most species of insects.

This undermines the ad’s key assumption. Killing more species than other insecticides do could actually make Omnicide a worse option for home gardeners—especially for those who don’t know which species to attack—because using it indiscriminately will kill beneficial insects.

The ad never suggests that using Omnicide will guarantee healthy plants—it just argues that Omnicide is the best option available.

Irrelevant. How profitable Omnicide is for the manufacturer has no bearing on whether it’s the best insecticide for home gardeners.

The ad is purely focused on the best insecticide—that is, the best killer of insects. How it performs against plant or mammal pests is irrelevant. We also don’t know whether other insecticides perform any better against such pests.