I think the concern may be that people who care about the prestige (VCs/employees/acquirers, mostly) also will ignore the denominator. Saying "we're a YC company" holds more cachet when there are 10 companies per batch and you can name all of them than when there are 120 companies per batch. There seems to be a mental switch that people flick when the set of options goes from "can hold all of them in my short-term memory and understand what's special about each of them" to "oh, this is just an instance of X", and it's the same switch as between monopoly vs. commodity businesses or between founders vs. employees. People are arguably wrong for having that switch, but they have it nonetheless.

While the percentage of companies accepted may be shrinking, aren't the size of the batches increasing?

Regardless, with every batch that graduates YC, you are effectively splitting the amount of time Partners and Mentors can dedicate to each individual company by an even greater amount. And while YC has added new Partners and Mentors, I'm not convinced that your supply of expertise is growing fast enough to meet the demand that you are creating with each new batch. Then again, maybe you are. I'm sure my perspective isn't the greatest.

I don't want to seem overly-critical, I'm still a fan of YC and I continue to recommend it, but I'm not sure the class of '17 will get the same value that the class of '07 did.

It seems like there is a much larger group of mentors too, so the mentor time per team is probably constant. Also, there's a network effect of YC companies helping others. It's kind of like McKinsey getting added benefit from being the largest strategy consulting firm. More partners to reach out to.

(I have no horse in this race - no affiliation with YC or YC funded companies)

Well I was in the class of '07 and I can tell you that this is simply not true. Over the past 10 years YC has added many more mentors, there are many more alumni to help you and to seel to, their is significantly more experience behind the advice, and the brand is significantly more powerful.

So you feel that the ROI is greater for companies going through YC now than it was 10 years ago? I suppose it's true that the network of founders has grown significantly, but it's hard for me to imagine that a founder in the class of '17 becoming the head of the YC Accelerator.

Wow - I'm not sure what you are basing that on but it can't be any knowledge of the current class.

It has nothing to do with the current class. You're missing my point. You could have the next Elon Musk or Marc Andreessen in the current class, and given that you guys are YC, you probably do.

My point is this: for every person added to a network of individuals, the opportunity to create strong bonds with each person in the network is reduced, even while the value and strength of the network itself is increased.

A larger network means more opinions, more expertise and more connections (every person added to the network brings their own network of connections). Thus making the network more valuable to each individual member. However, once networks reach a certain size, that value is often extrapolated indirectly. Someone asks someone else to ask a third person a favor, because the second person knows the third better than the first. Thus, the likelihood or ability for each member to form strong relationships with everyone, or the more VIP members of the network, decreases.

This not a knock on YC or the current cohort. I'm a big fan of YC and I'm fully confident the W17 class is as quality as every other class that's gone through, but network dynamics shift as quantity increases.

With all due respect, even though that might be true, that still doesn't necessarily conclude why YC has to continue to grow and take a larger and larger number at the pace that it is. It's clear what you're saying is true. Startups are trendy now and part of popular culture, therefore demand for doing them and number of applicants, as well as quality, go up. That still doesn't mean YC has to expand at such a massive and incredible pace. However, I do think you guys know more about it obviously than us from the outside. Keep up the good work. :) Just giving my .02