You're right to be confused, because the article is trash.
And here's why: try to ask yourself what is Ollis here really trying to say. I'll summarise his points for you:
1. Testing is important and needs to be done right.
2. NAPLAN is awful, because
3. it is "a tool to harvest information and rank schools, why is a dangerous dangerous development".
The rest of the article then repeats point 1 for some reason.
What do you end up learning from Ollis' article? Nothing. Point 1 is obvious and everyone agrees. Point 2 is contentious, and he offers point 3 to justify point 2. He claims that NAPLAN is turning into a tool that harvests information and rank schools is a "dangerous development".
NAPLAN harvesting information can't be the reason why it's dangerous, because that's exactly what a test is inherently meant to do. Ranking schools is the whole point of NAPLAN right from the start and Ollis agrees, as he claims that Naplan was created to "keep track of schools that are letting the system down" (in other words, ranking). So clearly, it seems that NAPLAN has not morphed into something that harvests information and ranks schools, because this is exactly what it has always been doing, and so there is no morphing and Ollis is contradictory on this point. Furthermore, Ollis claims a dangerous development from this without explaining how exactly is it that those aspects of NAPLAN dangerous, so there's nothing to take home from this statement.
In addition, he also claims that schools teaching the contents assessed in the NAPLAN test is incongruent with what he calls "genuine educational goals". He has not explained what those goals are, and hence has not justified the incongruence he claims.
I'm not defending the NAPLAN test. I just find that Ollis' article says a lot about absolutely nothing. There is literally nothing worth taking away from his article.
Critically analysing and debunking the articles you read is good practice for uni.