This is an oft-repeated and utterly bogus argument. You can simply change how many spaces a tab is in your own IDE. And in decades of programming in IDEs from B

This is an oft-repeated and utterly bogus argument. You can simply change how many spaces a tab is in your own IDE. And in decades of programming in IDEs from Borland to Visual C++ (since there were separate 16- and 32-bit versions) to Xcode... I've never seen one default to five spaces. Four spaces is, by far, the most common. People who don't understand tabs are akin to those who don't understand styles: Doomed to laboriously dick around with formatting, and make work for everyone else.