You already mentioned, but I think it's worth repeating -- in my view, the best startups do not take the YC deal anymore. I think partly it's because YC is a victim of its own success (the startup ecosystem is now much more developed, and other incubators and VCs bid at higher valuations); partly, the brand has fallen somewhat. Also, my guess is that a lot of the best people who would have used to start a startup, now join/start a lab, or sometimes, a nonprofit.

Some startups (and I presume, their incubators) do achieve extraordinary growth due to AI, though. One example is Cursor -- a VC recently asked "on a ROI basis, which would it have been better to seed invest into, Anthropic or Cursor?", and the answer was actually Cursor due to its rapidity of growth + fast acquisition. (And, the incubators such as https://aigrant.com/ are a inspiration for me when thinking about https://surplus.dev/)

I'm not sure I see secular declines in this graph.
The largest signal for valuations is really just the state of the market -rather than how much progress is being made - are we in a bull market for VC or not. You'd have to look a lot further to see how much faster AI is making them.

Anecdotally I do hear revenue is ramping way faster than it used to - that has also led to a shift in valuation/round expectations i.e. $10M ARR is the new $1M ARR. AI drastically increases your ability to build and deploy software rapidly which allows both you and competitors to scale more rapidly. This should lead to a world where VCs eventually get to "buy" way more revenue for a given dollar, but we also are going to see declines in profitability, both because tokens decrease gross margins and because increased product competition will mean increased sales and marketing spend, service level requirements etc. YC is going all in on vertical/domain-specific AI e.g. find a niche, build something that probably a 100 others can, and then go use our platform to market harder and ramp distribution as fast as you can.

Some thoughts from a product manager working in tech:

1. AI increasing productivity allows startups to do more with less. I wouldn't necessarily expect it to significantly accelerate growth in general as coding speed is rarely the bottleneck for scaling products. You still need to grow your team, reach your target audience, find product-market fit, build your brand, convince customers to change habits, etc. This all takes time and effort. Coding is a surprisingly small part of it in most cases, especially for startups that aren't lacking funds for hiring engineers (which I'd expect to encompass ~all of the YC-backed ones).
2. None of your metrics is actually measuring the rate of growth. You are measuring the absolute size (valuation) of a company after a certain amount of time passes. It's entirely possible that the startups are indeed growing faster but are smaller than before, sold off earlier or taking less investment (making the post-YC valuation less accurate).
   A few effects that would incentivize this:
   (1) AI enables doing the same work with a smaller team, decreasing the need for external investment and therefore founder dilution, lowering founder incentives for high valuation (for a founder 30% share in a $50M company is actually better than a 10% share in $150M one, as they maintain more steering power)
   (2) AI makes copying a product easier, increasing the bargaining power of larger incumbents offering acquisition
   (3) Advances in general-purpose AI are reshaping markets and societies faster than any technological change before, increasing the risk of a startup becoming irrelevant despite early success.
3. AI capable of significantly accelerating coding in non-trivial use cases has only been available since mid 2025 - early 2026, depending on who you ask. The benefits of AI for coding that we're discussing today would not be visible in your data yet anyway.

On all of the graphs, the most recent data point is the largest or second largest. So the obvious takeaway is that YC companies are growing faster. 

I guess you could accurately describe it as 'faster than before but not wildly faster', but it feels like the post is going farther than that to downplay it (including the headline that doesn't really match the data, "YCombinator companies still aren’t growing faster due to AI").

Maybe you're too anchored to last year's analysis? I imagine that, if the data had looked like this a year ago, then the content of last year's post would've been pretty different.