[bob1029]

I feel like you are arguing more for namespaces than modules.

Having a hierarchical naming system that spans everything makes it largely irrelevant how the functions themselves are physically organized. This also provides a pattern for disambiguating similar products by way of prefixing the real world FQDNs of each enterprise.

[adrian_b]

As another poster already said, providing namespaces is just one of the functions of modules, the other being encapsulation, i.e. the interface of a module typically exports only a small subset of the internal symbols, the rest being protected from external accesses.

While a function may have local variables that are protected from external accesses, a module can export not only multiple functions, but any other kinds of symbols, e.g. data types or templates, while also being able to keep private any kind of symbol.

In languages like C, which have separate compilation, but without modules, you can partition code in files, then choose for each symbol whether to be public or not, but with modules you can handle groups of related symbols simultaneously, in a simpler way, which also documents the structure of the program.

Moreover, with a well-implemented module system, compilation can be much faster than when using inefficient tricks for specifying the interfaces, like header file textual inclusion.

[ludston]

It is irrelevant until you have 4gb of binaries loaded from 50 repositories and then you are trying to find the definition of some cursed function that isn't defined in the same spot as everything it is related to, and now you have to download/search through all 50 repositories because any one of them could have it. (True story)

[layer8]

Modules don’t imply namespaces. You can run into the same problem with modules. For example, C libraries don’t implicitly have namespaces. And the problem can be easily solved by the repository maintaining a function index, without having to change anything about the modules.