As someone who uses Python since 2004, you got it backwards.

Python was popular before because it's very nice language. People wanted to use it for science to, so they wrote very good scientific libraries for it.

R was very popular for non-neural-network ML some years ago, yet it wasn't picked up for NN, because R kind of sucks for general programming. As the joke goes, the best part of R is that is a language written by statisticians. The worse part of R is that is a language written by statisticians.

Python was growing at accelerated speed year on year well before neural networks.