There is a huge difference between asserting something is treif and asserting that it is not up to a standard of kashrus that you personally follow. There are many things that I don’t eat possibly because I hold by a different hashgocha, but I know that these things are minimally kosher. Certainly someone who eats them is NOT eating treif (I am not talking about products with additives).
It is “treif” for me to eat rice and beans on Pesach. Does that make it unkosher? The problem specifically with today is that many additives and chemicals are introduced into products that are otherwise l’chatchilah kosher. Or, as was pointed out, they are produced on machinery that might have a run of something unkosher (though that has never made sense to me, because i.e., chocolate bars are produced so en masse, it would seem that they would use one machine for all the plain milk chocolate, another one for the milk chocolate with almonds, another for the Nestles Crunch type, etc.). In any case, we DO have to be vigilant nowadays. Life was much simpler when the only ingredients in products were simple and unadulterated.