It's basically an alkalining process; it can be done with ashes at it's most basic. But, and it's a huge but, it not only changes the chemistry of the corn and makes it become a dough instead of a porridge type ....
When I looked it up the article said the nixtamalization process in and of itself just turns the corn (maize) into hominy. The homily then has to be dried and milled into flour. None of those stages is really what I'd think of as a porridge. Hominy is just a fluffy, naked corn kernel.