Hi Fernando.
You don't insult anyone
; but it's your personal opinion. There are hundreds of reasons to consider Bable a language.
I suppose you're quoting directly from the RAE when it says that Bable is a dialectical variant of the old Astur-Leonese (not Castillian), but as a professor from my university (UCM) used to say: "the RAE doesn't normally go beyond Castillian" and she was being ironic since she could have said Spanish instead.
The tendency nowadays is to become more accurate (Descriptive Linguistics) with languages. In fact, the term dialect has sometimes been criticised for several reasons, but I'm not going deeper into this topic.
Human Language is nothing but a set of sounds, rules, etc... that we use in order to communicate. It entails some cultural aspects too. But if we follow the RAE's own description; Bable, although it's labelled as dialect, should be considered a language, isn't it contradictory? Yes Indeed.
It has had almost no literature for centuries, remaining a dialect spoken in some localized zones of Asturies.
The fact that it has had almost no literature for centuries doesn't mean anything. I could start mentioning hundreds of Languages which lack, not only literature, but a written code as well. That concept is related to Prescriptive and Diachronic Linguistics and is considered old-fashioned.
It is a dialect of castilian and its roots come from the ancient medieval language called astur-leonese.
Bable is not a dialect from Castillian. In the Middle Ages there was a period of Diglossia between Castillian and Bable; linguistically speaking, this would mean that they were different languages. Thus, if we had to keep on using the term dialect, we'd better say that Bable is a dialect from Astur-Leonese due to the fact that Bilinguism takes place between two different languages.
It's a bit messy because you're playing around with the term dialect and mixing Astur-Leonese with Castillian and Bable.
I know it's hard to believe, but the RAE has changed its views upon words constantly and it will go on like this because languages are constantly "evolving".
Decades ago Català was not even considered a proper language. Now, if we know that Bable has a lingusitc corpus, a thesaurs, a lexicon, dictionaries, a grammar, morphological and morphosintactical rules (essays on it), a group of speakers, it's institutionalised (Language Academy, Universities, Newspapers, etc), literature, historical background and variants within it, what else do we need?
.
The problem here is that I can only see it from a linguistc point of view.