Exactly. I've carefully tailored my feed so it provides me with a huge amount of dog photos. Now every time I get on there my mood is usually boosted seeing cute dog photos and videos.
It's as if responding to someone that said that one can never find any positive stream on Instagram, when people actually complained about what Instagram, at its majority, and as is used by most, is.
Media broadly is what you make of it. Turn on the TV and flip to CNN, I'm sure you'll be depressed within a couple minutes. At some basic level the burden of information curation rests on you - the human. You can't keep blaming CNN, Instagram, Facebook, Buzzfeed, etc etc ad infinitum.
At some point you have to step back and take the responsibility of information intake into your own hands.
That's not to say you don't have a valid point. You absolutely do have a valid point. But it's not as useful of a point as you're suggesting imo.