In this case slang, argot, etc. are obviously not dialects. The same slang words are used troughout the country regardless of the speaker's ethnicity, place of residence and his or her actual accent/dialect (if there's any). They change pretty fast, with a life cycle often less than a decade, and we can safely say that they are NOT dialects (as a stable regional varieties of the same language).
It's all ultimately a matter of definition. People simply haven't found a good set of rules for classifying language variation. Languages are ultimately too amorphous to demarcate so starkly.

But I'd posit that the life expectency of a manner of speaking has no bearing on its status as a dialect. If you attempt to quantify dialects and make exclusions based on life expectency, you're doing something completely arbitrary and useless.

Even though argots and jargons have little to no traction among the majority of the people and die out quickly, they're still classifiable or subsumable as dialects in the sense, as the long-standing English dictionary Miriam Webster points out, that they're peculiar to certain social groups, even if not to particular regions or ethnicities (take for instance, in English, the Irish Travellers' Cant).

As for Olya's "points" - there are Russian linguists who speak half the English that I do who know twice what I do about my own language. You don't have to be native to Russian or eschew russki mat to have knowledge of something that's rather topically linguistic. It seems you harbor some fairly disturbing elitism/nationalist-chauvinism/linguistic fascism with reference to "foreign professors" of the language (not to mention colloquial or rough manners of speaking).

I mean, it might actually benefit you to "talk seriously" on the topic even if your "supreme Russian-ness" somehow obviates any hard thought into the Russian language.

And Ramil, the US has an English literacy rate of 99% (.4% lower than Russia) and we've still got dialects. You're not going to tell me that .4% difference in literacy makes the US an "illiterate" country that consequently contains dialects?