Yes, it is directly relevant. And sure, many languages can dream of that level of use, but most other languages do not have the luxury of being there, and then making decisions that demonstrably do keep some people from using even a language as widely used as Python is worth at least thinking about. Especially when category of languages that does this is already dominated so thoroughly by Python.
Do you actually have any data on how many people don't use Python because of significant whitespace? I suspect it's actually a very vocal minority -- it's about as well-formed of a reason as refusing to use C++ because it requires semicolons.
It's a matter of personal taste, so it does not need to be "well formed". These things are more religious questions than about rational arguments. As for numbers, no, I don't. All I have to go by is the number of people I know or have met that dislike it. And so I know it is polarizing, but beyond that it is guesswork. The point was not to claim that it is some massive proportion of developers, but to point out that decisions of taste are not inconsequential.
