There might be errors, or perhaps incorrect assumptions, in that article.
The overall increase of 5% is only true if everyone stays in the program. (and that's only true as an average of all the states based on 2018 assumptions).
But you know what happens when you assume.
See this link for more detail:
http://acasignups.net/18/06/05/my-official-2019-rate-hike-project-explainerThis shows that the average rate of increase will be just over 15%. That is the only "hard" data because these 9 states and DC are the only ones who have posted their 2019 changes.
However, that 15% is only as a result of what the trump administration is doing (referred to as 'sabotage' by ACA Signups). Without trump's 'sabotage' the rate increase would only be an average of 3% or so.
So, it's not as "rosy" as your referenced article makes it out to be - sadly.