My point is that "readability" is composed by many factors, not just one. What is "readable" to some will not be "readable" by others. It depends.
For someone who knows Fortran, learning a Fortran-like language is easy (like C or JS). For someone who knows Common Lisp, Clojure is easy. But for someone who knows Fortran, Clojure is less familiar, hence the code will, on a glance, look less "readable".
The other factor is if something is "simple" by itself.
Most of this view comes from Rich Hickey, who wrote Clojure. He discusses "readability" or "simplicity" rather, in his talk "Simple Made Easy". If you haven't seen it before, do yourself a favor and watch it: https://www.infoq.com/presentations/Simple-Made-Easy/
He'll explain it much better, and with further points, much better than I ever can.
I don't disagree with your overall point, but I actually wonder how true that is. If you spent years working in Brainfuck, and had never touched Python, I suspect it would take a bit of effort before Python was as readable to you as Brainfuck.
So your argument is that all code is as easy to read as long as you have done the work to get familiar with it? I hope you understand that it is bullshit. Brainfuck isn't easier to understand than python no matter how much time you spend with brainfuck.