> Children don’t learn languages faster than adults, but they do reach higher levels of mastery.
> adults simply plateau at a non-native level of ability, given continued practice.
If adults plateau and kids don't, kids do learn languages faster.
> adults simply plateau at a non-native level of ability, given continued practice.
If adults plateau and kids don't, kids do learn languages faster.
The article considers "learn" to mean roughly "fluency", short of native mastery, and adults tend to reach fluency faster, then plateau.
So depending on nuance, you and the article are both right in some sense.