Why does the Google Analytics module restrict uid? When I try to insert the [current-user:uid] token for a custom dimension in the Google Analytics module, it gives me an error that this is a forbidden item.

However, reading through the GA Terms of Service, I can only find a vague statement saying only "non-personally identifiable information" is allowed.

The GA module is the only documentation I have found that explicitly states the uid is forbidden.

Wouldn't an id be allowed because Google has no way of retrieving the Drupal user's information?

Does anyone have a reference to where in the GA policy they disallow uid?
There is nothing specific in the GA documentation that forbids it. There is actually a section in the GA Help which explains how to use user ids: Benefits of using the User ID feature, so using user ids is not forbidden by GA at all.

Why it doesn't work in the GA Drupal module is because of this paragraph, as stated by one of its developers (found here):


  If you upload any data that allows Google to personally identify an individual, your Google Analytics account can be terminated, and you may lose your Google Analytics data.