This team has every good reason to succeed: they spent 2 years of their life working together building something that's now getting significant traction - and making them money.
Every fundamental metric indicating whether the business will work or not were established facts. That should put them head and shoulders over anyone else.
Given all that, it's hard NOT to feel emotionally invested after 2 years. And it's hard not to want to spend time processing the experience the way they did.
At this point, it doesn't matter why they didn't get in. It would be great to know, and yes, it's awesome that they got some actionable feedback -
Actually, I want to say something about that too. Even if the feedback isn't what you wanted, shaolin69, it's all the more valuable because it's coming from someone who isn't like you. I agree with your priorities - especially your viral loop tricks (way to go on that, by the way). But I hope you'll tuck it away somewhere for the day you scratch your head and wonder "ok, what can I do now to boost traffic?"
But. As I was saying, it doesn't matter why you didn't get in. You still know you have the makings of a successful business. YC's rejection doesn't invalidate your track record. So be encouraged! I'm glad to see you took advantage of your time stateside to look at other accelerators and got some interest. Best of luck, looking forward to hearing your success stories!