> the quality of available clothing across the world have fallen

Do you have a source for this? Anecdotes along the lines of "they don't make 'em like they used to" are incredibly common but often fail to stand up to scrutiny.

Circumstantially, the dominance of fast fashion, produced quickly and sold cheaply, suggests that some aspect of production is more "efficient" than historically so. I've seen YouTube fashion experts explain exactly how (lower quality fabrics, simpler and less durable sewing, cuts that use less fabric than would be so in higher quality garments), and while I'm not experienced enough to corroborate, they were convincing.