> As to the rest, I'm sure you know "species" denotes "a population capable of producing viable offspring." So why would we ever use a different word?

A different word for what?

The term "species" predates the theory of evolution. If you study taxonomy and phylogenetics, you will quickly find out how arbitrary it is and that there are many exceptions.

> A hybrid, by definition in the context of biological evolution, is "offspring produced by more than one species." That's an explicit indication regarding the presence of distinct populations or a statement about the capacity to produce viable offspring.

You were talking about the general definition of the term, not about its application in a particular context. And again, not all inter-species hybrids are infertile. See for example bovine hybrids: https://en.wikipedia.org/wiki/Bovid_hybrid

In particular, beefalo is a fertile hybrid breed resulting from crossing species of different genus. https://en.wikipedia.org/wiki/Beefalo

Similarly, many commercial plants are result of hybridization. The [brassica] https://en.wikipedia.org/wiki/Brassica genus is famous for this, see https://en.wikipedia.org/wiki/Triangle_of_U

> Like taxonomy as you mentioned above, asserting primacy to the factor of a population is more on the arbitrary side of things. It's a blurred line in many respects. Viability, however, is not.

Turns out it is. This is why we are usually talking in terms of populations.

> Most people tend to think of species as a label.

And they would be right. It a rather arbitrary label that predates the theory of evolution. What is species and what is sub-species is not well defined and depends whether one is "splitter" or "clumper".

> mixed-plant offspring "hybrids" is, for lack of a better description, kind of missing the point in so many ways.

You haven't demonstrated what point.

The rest is pseudoscientific nonsense anyway. You clearly lack the understanding of terms like "gene flow" and are instead trying to describe "diffusion of alleles between populations" in a paragraph of blabbering.

> So yeah, "hybrid" absolutely does imply that the offspring are not viable

I have clearly demonstrated that they are viable.