T-Mobile isn't exactly going out of its way to let people know this exists. It's not featured in the way you do for a plan you envision as the future cornerstone of the business.
I have this plan. Had to call customer service to get them to honor it. Bit of a hassle, but they did it. It's not available in their regular plan settings; clearly they'd rather people buy the more expensive plan with unlimited minutes instead. I won't be particularly surprised if they discontinue it at some point soon. For the time being, the plan meets my needs quite well though.
T-Mobile isn't exactly going out of its way to let people know this exists. It's not featured in the way you do for a plan you envision as the future cornerstone of the business.