C++ is dead there (and in many other places). The closest thing is Golang and Swift (and perhaps Rust). That doesn't mean there are no C++ jobs, but you'd need to look for them elsewhere. Why is that surprising?
I don't see why C++ should be dead in startup world. With the emerging of AI, machine learning and fintech, you would think there's plenty of opportunity for using C++. I know there are plenty of C++ jobs in google/facebook, banks(i work there), but still, 0 startup on AngelList is surprising, I was thinking it's at least as (un)popular as java and C#. I even found a Haskell shop there.
C++ might be used. By calling it from Python or Java or Haskell, which will allow you to iterate 10 times faster than using it directly. Startups are trying to prove that their business idea works. This idea usually involves using existing technology to solve some business problems, rarely it requires development of lower layers of the stack. This may come later - or may come never. You can easily use machine learning without knowing what C++ is.