From what I've read, a lot of languages that have nominative-accusative marking have only this type of marking. However, languages that have ergative-absolutive marking in some contexts typically also have nominative-accusative marking in other contexts. These are called "split ergative languages." (See the article in Wikipedia for more detail: https://en.wikipedia.org/wiki/Split_ergativity)
But a lot of people talk about "ergative languages." The article just cited states that "most of the so-called ergative languages are not pure but split-ergative."
Are there really any languages that have ergative marking but no nominative-accusative marking?
And why, in general, do people refer to split-ergative languages as "ergative languages"?