That's a silly slogan, I get the appeal but I think it's just an easy way to avoid taking responsibility for our own decisions.
At the very least, there is better and worse consumption. It is utter nonsense to say that buying something made possible by modern day slavery is the same as paying a local artisan for something.
I don't think "yeah sure, that'd be great but if we all started doing good things it wouldn't work!" is a particularly valid critique. We are nowhere near the point of too many people buying second hand clothes.
Yes, cheap stores are common.
But the most valuable brands in America are not at the cheap level, they are things like Nike, Levi's and The Gap. Hell, even in progressive bastions so many people are rocking Arcteryx, REI etc, none of which are cheap.
Again, go to any downtown, look at the outfits and consider how much they cost. Just the same as people wearing hundreds of dollars in jewelry (yes, there's costume jewelry but that's not what most folks are wearing downtown.)