I'll counter that if you add a type checker to one of these languages, such as TypeScript (for JavaScript) or mypy (for Python), then all of those problems go away.
I'm personally particularly excited about the possibilities unlocked in the Python community by type checking, which I wrote about recently here: https://dafoster.net/articles/2021/01/26/python%27s-type-che...
Additionally, RE "Poor performance" the author is presumably talking about CPU-bound performance. If you happen to be writing network-based or I/O bound programs, which you always are in JS/TypeScript and sometimes are in Python (for web applications), then the effective performance is more affected by the network/database/disk than the programming language.