There's a reason your parent comment expected some to be "an article". It is the plural of a(n). It's just that the term "article" was defined not to include it. There's a different word for the part of speech.
No, some is not an indefinite article, it is a quantifier word, just like "few" or "many". This is most easily visible in the fact that you can say "A: How many pears should I buy? B: Just buy some." - which would not be possible for an article, which must always be attached to a noun (you would never answer "Just buy a" in response to that question).
Articles and quantifiers are different parts of speech in most grammars. Articles are specifically different in having no independent meaning, more similar to prepositions than to adjectives (which some is classified as in its use as a quantifier that we were discussing here).
English just doesn't have an indefinite plural article. This is not actually that uncommon - German has the same property, for example.
