I agree thoroughly with this - it's fantastic for building something quickly. If I need a quick script to do one-off data processing there's nothing better. My biggest problems with it IMO with respect to maintainable software are:

- The syntax required to build libraries feels like messing with the internals of the language. Defining various methods with reserved names that have 4 underscores each doesn't really feel like something you are supposed to do. The code becomes harder to read and messy IMO.

- Runtime type checking is great for iterating quickly, but bad for stable software.

- Encapsulation is only enforced through external tools, so if you aren't using those religiously you end up with problems with tightly coupled modules.

- Dependency management is not a good experience. Understanding the different rules about where python pulls modules from is hard. Venv makes things a bit better, but even then it's still a bit opaque. It means that I often spend more time on getting external dependencies aligned properly than writing any python when working on a python codebase locally.