The Zen of Python is not much more than a meme. As a nearby comment pointed out, Python doesn't follow it in many ways (explicit vs. implicit comes to mind), and it contradicts itself in several places.
"Readability counts" might be the one exception, at least early on in the language's lifetime. Nowadays it could be argued that even that is diminishing.
But readability is often overlooked by most programming languages, which is a mistake. Programmers (should) spend more time reading than writing code, so it's very important. It's also very difficult to get right, being so subjective, but GvR has a good eye for it, and he made good design choices to balance it with expressiveness.
Readability is also crucial for a language being welcoming to newcomers, and new programmers in general. I think that Python is still the best first language for people learning to program. This is likely the biggest reason for its adoption and popularity today.