Yep, you are indeed correct.

The correct comment should be: This article is about a specific class of insecticide, not a herbicides.

Coincidently, I learned that Neonicotinoids means 'chemically similar to nicotine', I thought that was a coincidence at first.

A lot of “compounds of interest” such as nicotine, opium latex, and capsaicin evolved as part of the natural defense mechanisms of plants against insects and herbivores.

So "nicotinoids" means "chemically similar to nicotine", and... "neo-" means new. Some of the literature refers to nicotinoids and some to neonicotinoids.

What I haven't been able to figure out is if there was essentially a "second wave" of nicotinoids that someone -- a scientist or marketer -- figured was deserving of the "neo-" prefix.

One random, uneducated guess from me: Maybe the "neo-" prefix is only for those that don't show up in nature, so they have to be produced in labs, and are thus "new" to the environment?

Indeed but people confuse the two. Almost all of the issues with pesticides come from insecticides specifically. Insectices are designed to kill animals after all.