Have documentation communicate how hook_hook_info() really works

I realise, after quite a bit back and forth, that the groups defined by hook_hook_info() not only applies to the module that implements the hook, but to the entire system and all other modules. This is something that the documentation not communicates very well.

For instance, the Rules module implements hook_hook_info() and defines that some hooks lives in 'module.rules_defaults.inc'. Without knowing this, I had my module to implement hook_hook_info() as well and the array returned by my implementation dictated that some of the hooks invoked by Rules would live in 'module.rules.inc'.

Now, the array returned by my module would seemingly apply to all other modules as well. That is; the core would have looked for the file 'module.rules.inc' in all other modules as well as my own. However, in this case, the Rules module already implemented hook_hook_info() which led to the system to keep track of two files : 'module.rules_defaults.inc' and 'module.rules.inc'. This again is not supported, as 'group' should reference a single value and not an array. Thus, the system would not have found neither the first nor the second file due to this.

If the above, as I understand is how it works, is correct, then I'd say one should be careful with implementing hook_hook_info() as you might override something another module relies on.

I'd say at least the documentation should describe this. Any thoughts on that?

References:

module_invoke
module_hook

How to recreate the above?

1. Install the Rules module.
2. Create your own module and have it to implement hook_hook_info() :

function yourmodule_hook_info() {
  $hooks['default_rules_configuration'] = array(
    'group' => 'rules_default',
  );

  return $hooks;
}

3. Have your module to also implement hook_hook_info_alter() and dump provided hooks:

function yourmodule_hook_info_alter(&$hooks) {
  dpm($hooks);
}