They actually do say "unlimited phone, and 7GB tethering". It's very explicit, and limited tethering is a specific part of the "unlimited phone" plans. And as the article says, if you want more tethering, you are able to add and pay for that separately. The issue is people bypassing the tethering limitations.

I'm guessing people in the marketing department would disagree. They'd argue that a lot of consumers don't know how much a gigabyte is so even a comparison between 120GB and 12GB is less appealing to them than a simple term: "Unlimited"