you're definitely right, it is limiting. The thing is we're talking about water-based screenprinting, not DTG. The screenprinter made this sample prints for me, and didn't pass the shirts in an oven or a heatpress or anything, saying that they dry out almost instantly. I am a designer, not a screenprinter but i have gathered that you almost always need to heat-set your print, whatever the tecnique.
I am kind of buffled here...
Water based inks, be it for screen printing or for direct to garment, need to be heat set for washability. Being water based, they can air dry and feel dry to the touch. But unless you heat set them the inks will more or less wash out.