I’m puzzled by the comment as well. On RYM, as voted by thousands of music consumers, it’s their second best album: https://rateyourmusic.com/artist/sleater_kinney (trailing the best by only 0.01 point)
On Metacritic, not counting the career spanning boxset, it is even considered to be their best album: http://www.metacritic.com/person/sleater-kinney
So I guess the remark in the article is mostly anecdotal in nature.
They’ve been around for years.