I've been making my own tortillas for a decade and I can tell you there's nothing newly wrong with the corn flour. It's the same it's always been.
Yeah it's always best to have heirloom with minimal processing, but I'd rather have 100 homemade tortillas with basic nixtamalized corn flour for $3 not $30
They have a good point. I did research into cornbread for a project and it's suffered from the same issue as tortillas. Most cornmeal that you buy in the store nowadays tastes like sawdust and has to be enriched with a bunch of stuff to make it preserve longer. Originally southern-style cornbread had zero added sugar in it, but most recipes nowadays call for a tablespoon of sugar to balance out the flavor of the sawdust cornmeal so it ends up just tasting like nothing. You don't do that if you use good, heirloom corn, and it actually has flavor.
It ultimately comes down to the quality of the corn and the method that they use to process it and to maximize profits. Stone ground cornmeal yields a better product, but is less efficient.
I'm going to be honest here, I'm highly skeptical of the quality of cornmeal leading to lower quality tortillas. This is mainly because we already know why they are bad in the states. Not to mention the comment iteself is written like it was a conclusion made in conjecture.
Please cite the study you read/wrote that concludes cornmeal is the reason behind why corn tortillas are so bad in the us and that the deterioration of cornmeal is what led to it.
The quality of any ingredients has a huge effect on the intensity of flavors. Check out the differences in free range/ field chicken eggs vs indoor/caged/ feed eggs
You ready for an insane trick? Store your corn tortillas in the fridge. When you're ready to use some (preferably a lot at once) grab the number of tortillas you want, plus two. Heat up a pan or griddle to medium/medium-high heat and carefully place the stack of tortillas on it, dry. Let that go until you start smelling the tortillas without standing over them, then flip the whole stack. Let this go until you smell the now-bottom tortilla starting to burn, then flip the stack one last time and let it go until the other end's tortilla starts to burn. Remove the two burnt tortillas and place the rest in a tortilla warmer until you're ready to enjoy your beautifully steamed but not damp corn tortillas.
Also, if you're not warming your flour tortillas, you're really missing out. If you have a gas stove, turn the flame on low and heat up the tortillas individually directly on top of the burner. Like-fresh every single time.
Unless you're eating at a local taqueria that makes their own (or you know a friend who makes their own), they're not wrong. Commercial corn tortillas are fucking gross, and I hated them until I had fresh ones.