The other thing to factor in is that most of the people that are experiencing premium increases are on plans that don't meet the "minimum level of care" as mandated by ACA. Those plans that no longer qualify are often the types of plans that lead to the horror stories of people being kicked off of plans after becoming sick (rescission), lifetime maximum amounts, etc. Insurance companies were saving a lot of money due to those brutal practices. Part of the intent of the ACA was to eradicate those practices, which ultimately protects the people that were subscribed to those plans, and who didn't understand they were at that type of risk.
In other words, if you were subscribing to a crap plan, your premiums were artificially low in the first place. It's kind of a degraded case of the people that are complaining that they can't any longer go insurance-free. The law of the land now is that everyone has to participate, in order to help take care of our sick and injured - so that means that our insurance plans all have to have a basic level of quality.
I would bet that if you restricted your search to the people that originally had plans that met that basic level of quality (which is really not all that high), you would find that their premiums have gone down.
(Obligatory data point: I'm self-employed in washington, have had a Regence BCBS plan for $540, and my monthly premium will go down about $150-$200 / month for similar care.)