For certain items it is part of the cost for the quality of good being procured at a given price point. I’m sure there are no-label options of equal quality and comfort, but the process of finding those options is a much greater (time) cost than the item itself is worth to me.
In a different context, if an artisan knows they are the best (by a large margin) and put their mark on every item produced, few seeking the artisan for their quality would stop using that artisan due to the mark as the alternative would be inferior goods. Same thing but much bigger scale, with a dash of marketing and broken trust (brand acquisitions followed by bad products) thrown in.
I would understand if the choice were good quality with logo versus questionable crapshoot with no logo. That's not usually the option, though. Perhaps you can't just look at clothing and see whether it is quality or not? Look at the stitching and materials, for instance? I happily pay more for good quality, no-logo than, frankly, logo with middling quality.
In a different context, if an artisan knows they are the best (by a large margin) and put their mark on every item produced, few seeking the artisan for their quality would stop using that artisan due to the mark as the alternative would be inferior goods. Same thing but much bigger scale, with a dash of marketing and broken trust (brand acquisitions followed by bad products) thrown in.