I don't think the article lists just one downside. For example It's also undeniably hard to parse, making it harder than necessary impossible to implement efficient refactoring tools and other parser dependent tools, for example.

> It has both amazing safeguards against programmer error and the ability to break all of them if you need to.

C++ has two main design constraints -- it comes from C and its abstractions should cost nothing. Those two have enormous benefits and drawbacks. Performance is one thing. Other languages that don't have those design goals/constraints have different benefits and drawbacks. It's easier to make a small shell util or in perl/python than in C++. It's easier to make a formally verified system in a functional lang than in C++ and so on. "The best tool for everywhere" meaning "if you need to use the same language to solve all N problems then C++ is best of the major and widely used languages" might be true, but it's also a pretty poor metric.