I would say std::string and std::io are special cases and somewhat atypical. Both have large performance overheads. I think the standardization committee blesse

I would say std::string and std::io are special cases and somewhat atypical. Both have large performance overheads. I think the standardization committee blessed existing implementationsite that had become popular rather than design one with performance in mind. Strings really ought to have been immutable by default.