I suspect that part of the reason is that the smaller shops I looked at were based in Brooklyn.
Brooklyn's agesim is much worse than Silicon Valley. Also, I was interested in the kinds of startups that are probably dominated by energetic younger folks. I do native Swift (Apple) stuff, and have a lot of experience with things like SDKs, and hardware control/communication.
The bigger shops tended to have a lot less interesting work, but were also a lot more "stolid" in their approach to recruitment.
Like I said, I was looking for work that I found interesting. I'm sure I would have been able to find work that was less motivating.
As it has turned out, what I'm doing now, is highly motivating, and I no longer have a desire to go back to the rat race. In the aggregate, I'm glad things turned out the way they did. A couple of startups missed out, but I'm sure they'll be OK. I'm not God's gift to programming. I know that I am doing great.