This is not just a YC thing, it's par for the course for most SV VC's. Their MO is to spread lots of bets around, expecting 99% of those bets will go to 0, 0.9% may just break even, and 0.1% may be the next Google, Facebook, etc. and make back far more than all their other losses combined.
That's a bit of a simplification and exaggeration, but the general idea is that if you want to raise money in SV you need a plausible case for how your startup will either become a unicorn (>= $1B valuation) or disrupt some really big established thing. YC also has appears to have a preference for technological advances - "breakthrough technology" - over the status quo.
Looking at your website I would have the same question as YC - competent-looking execution and product design, which if continued could potentially make it to >= $1B market cap, but it appears your business model is, at best, attempting an incremental improvement over UnderArmor and the like. What big problem are you solving, or big established things are you disrupting? What new market or industry are you creating? What breakthrough technology are you deploying that enables you to execute better than entrenched competitors in a way they can't easily replicate?
My sense is that's more along the lines of what they're looking for.