The problem with that for me is "like Python" implies a HUGE collection of libraries I can use to connect to pretty much anything.
With Python I can just search "python <thing>" and find popular, well-maintained, libraries to do <thing>. I can't do that with Nim. Most of the stuff I find seems to be 5-9 years old and have no updates since.
Nim allows you to use libraries for C and C++, as well as Python with the NimPy library, so the situation is not that bad if you don't mind getting your hands dirty.
They're poking fun at how sometimes you'll find a Python library that does exactly what you want with an interface that feels incredibly intuitive, but you end up finding out it was never updated to work in Python 3.x, only 2.x.
Though I'm not really sure how often that happens these days unless you're trying to write code that's using an old protocol that's fallen out of favor, like IRC, FTP, or Gopher.
However i do wonder how big the market is for "python, but faster and multicore". I suspect it is smaller than "c but safe".