See I consider flat ironing to still be natural because it can instantly revert back to its natural texture when wet. It's doesn't chemically alter the texture it just flatten and straightens out the curls temporarily.
With me for example there are days when I don't feel like dealing with my thick curls.
Sometimes after I wash and condition it, I blow it out, then I separate it into parts, comb and oil each piece and wrap/twist it up over night and it's soooo cute and soft.
It's just in a more "pulled" state. But if I wet it it would go right back.
To me perms and texturizers are not natural.