Which is why PEP-8 the Python code style guide enforces 4 spaces. This maintains consistency throughout the community. Also PyCharm one of the more popular IDEs for Python uses 4 spaces by default.

That's not what PEP-8 is for, it was meant to define the style of the standard libraries. A lot of people in the community voluntarily adopted it for their projects, but that wasn't its purpose.

Right, but this doesn't mean that the author can't use tabs to indent their code.