It aint about marketing. It is about giving the user an experience they don't have to worry. It is not about giving an abuser a green light they can get away with testing the limits of their patience.
It's funny, as a consumer i view it as a way to obscure the product and not make it clear what is actually being offered.
I don't care about downloading 20TBs, i'm not an abuser. I do however care about knowing the limits of my "unlimited" plan, which are very real and easily reachable.
It's funny how the limits of Unlimited can be reached in just a few days of youtube videos.
These limits don't feel like limitations on scammers and abusers. They are not designed to stop people from downloading 20TBs of data hoarding. They're limits that normal people reach easily.
Imagine a road having "no speed limit", but cops enforce a 200mph speed limit. That seems reasonable to me. They'll pull over people actively trying to break the sound barrier rather than merely trying to get to work going 80mph.
Now imagine that same road, with "no speed limit" - but cops pull you over at 80mph[1]? These aren't people actively trying to kill someone. They're normal, non-abuser people.
Tmobile's data limit isn't even remotely about data hoarders. My 5 year old thumb drive is 10x bigger than my Unlimited data limit.
[1]: This is a somewhat location dependent example, but over here (WA, USA) that's frequently obtained by "normal" people.