No, it doesn’t. Your indentation level matters, but provided your indentation is consistent, it doesn’t matter whether you use tabs or spaces, and the notion of “column” isn’t relevant to proportional-width fonts. If you’re worried about invalid indentation hiding from you, don’t use spaces for indentation with a proportional font—it doesn’t make sense anyway.
It matters more when you've got a statement broken over multiple lines. If you've got a function which takes a lot of arguments for example, lining them all up vertically can make the code a lot easier to read. This can be difficult or impossible to do with a proportional width font (and would almost certainly look very strange to anyone else looking at the code in a fixed-width font).
That's understandable. I agree that tabs would work much better than spaces with a proportional font. However, in the case of Python PEP 8 states that you should use 4 spaces. Not doing so will make it very hard to collaborate with other devs.
It's not that I think that proportional fonts couldn't work (even with python) It's just that I have concern about visually assessing indentation. Maybe it's time I try one and find out.
