A few days ago, when I seconded Kory Stamper's indisputable tweet that irregardless is a word,* @kellizuzelka replied " 'irregardless' doesn't even make sense ('ir-' cancels out 'less' and you have some awful double-negative nonsense)." And @soixante10 replied, "by what criterion 'irregardless' a word? Other than pple use."
Let me take these responses one at a time.
The response that irregardless is illogical won't stand up, because logic does not govern language. If it did, we would not have, for example, words like cleave and sanction that come with opposite meanings. And double negatives, though colloquial and shunned in formal written English, must be somehow consistent with English grammar and syntax because we can understand them. If I should say that double negatives don't make me no nevermind, you may wince, but you will have no trouble understanding the meaning.
When I replied to the second complaint, "Other than pple use," with "That's the crterion," @soixante 10 answered, "Was waiting for that!"
But that is the criterion. Look at how we got English in the first place. An illiterate British peasantry abandoned fundamental grammatical elements of Anglo-Saxon. Fundamental elements of Latin grammar were changed or abandoned in the creation of Italian, Spanish, and French. Beyond basic grammar, all manner of conventions change over time. We don't punctuate or capitalize now as writers of English did in the eighteenth century, we no longer go in for Latinate periods, and we see that the meanings of words shift over time.
As I have said before, people get tangled up by confusing actual rules of the language with conventions or personal preferences.
The only languages that are fixed are dead ones, like Latin and classical Greek. Living languages are what the people who speak and write them make of them.  Anyone who has even a rudimentary understanding of the history of the English language ought to understand this, and yet it continues to give people difficulty.
Now, to understand that anything goes in this way, does not mean that one has to embrace everything.** As far as I can recollect, I myself have never used irregardless except as an example, such as in this post. I don't care for it, I don't have to use it, I shun it. There are registers of English, from the most formal to the demotic, and you have access to all of them, to choose what suits your purpose and your taste.
In this regard, I am neither a prescriptivist nor a descriptivist but a rhetorician: I choose what I think fit for the subject, the occasion, and the audience, and I move up and down those registers freely. So can you. So should you.
* Ms. Stamper later tweeted, "I want a clone army of John McIntyres." I have offered to send her my fingernail clippings.
**If you imagine that my holding these views means that I have abandoned prescriptivism, I invite you to look at my post on holiday cliches.

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