Irregardless of language purist's approval or disapproval, irregardless has come into standard usage in the English language and is listed in modern dictionaries including the one in MacOS High Sierra and Mojave. As far as I know the only language that does not evolve through common usage is French.
Albeit as a linguist I should be more circumspect, I admit to being a presciptivist. That said ...
There's a major difference between
standard usage, which could be construed politely as
patois, and
literate usage. If you don't follow the latter, it will follow you out of the educational system and/or whatever high-paying job you might have. You'd normally be a liability rather than an asset if you don't speak the equivalent of
Received Pronunciation, which in the USA is referred to as Standard American and is generally the brand of speech most newsreaders use.
If one uses
irregardless and similar malapropisms as other than comic relief, then one falls on a spectrum of preliterate ~ quasi-literate ~ aliterate ~ illiterate — none of which leads to success in life.
L'Académie française takes things to the extreme (much as the Nazis did with German in the mid-20th century).
