so you agree?
"Word Origin and History for irregardless
an erroneous word that, etymologically, means the opposite of what it is used to express. Attested in non-standard writing from at least 1870s probably a blend of irrespective and regardless."
No, correctness is determined by usage, and Zikes is identifying that the usage has a fairly long history.
One could say the same things about starting a sentence with "so", or using "agree" backwards (the original sense was closer to the form "my statement agrees with you?"), or using "you" instead of "thou"...
Besides being a double negative that results in it not being equivalent to regardless, to your point it's been used for at least 100 years and is still considered non standard.