This is a pretty sloppy article, with a bunch of conventional-wisdom-as-evidence and no critical analysis of potential cause and effect. H&M as a stand-in for "cheap clothes", ignoring any number of other cheap clothing retailers that have come and gone for decades. Using only three datapoints for Levis 501 prices going back only to 2009 when claiming trends that go back 30 years, and when Levis 501s have been available under that name for 130 years and have been a common fashion for almost 70 years.
I do think some of the trends they call out are contributing for sure, but I don't think this piece really explains anything. They never really discuss whether people actually have fewer clothes or whether it's just that the clothes are cheaper. There's no real analysis of how fast fashion is changing.
And the whole idea that we _should_ be buying more clothes because "the economy is growing and wages are rising" is delusion. Wages have only just started to show signs of rising after decades of near-stasis, and the Fed reacted with big interest rate hikes that sent the stock market plummeting. A "growing economy" doesn't help an individual buy more clothes. Only rising wages can do that, or cheaper clothes prices. In the absence of wage growth, it's no wonder we've had a long-term decline in clothes spending. And because they overlooked this, the article also fails to consider that the fact that people feel they can't afford to spend as much on clothes is more likely a driving factor in the increasing casualization of work and society than the increasing casualization is a reason why we spend less on clothes.