Prioritization is not quite like data caps. This was initially reported as a leak but T-Mobile has since confirmed the change on their Twitter.
To make matters worse, many of these plans have additional caveats.
Starting September 20, T-Mobile is set to raise its "fair usage threshold", also known as its data prioritization limit, to 50GB from 32GB. It means your speeds will potentially nosedive if you're trying to use a congested tower at peak times (say, rush hour outside a train station), but should remain high if no one else is using the network.
Ray is quick to point out that slower download speeds - as a result of prioritization - only come into effect if you 1) have consumed over 50GB of data in your current billing cycle and 2) you are now connected to a sector of its network that is experiencing heavy congestion. And so you are aware, all carriers are doing this at this point, it's just that T-Mobile seems to constantly be tweaking (increasing) their limit. Oh, there are still limits, of course, but Tmo isn't alone there. Verizon's Beyond Unlimited and T-Mobile's One Plus plans run an additional $10 per month, per line.
Ever since smartphones began demanding more data, smartphone providers had no choice but to implement a soft data cap or deprioritize heavy data users in favor of those who use less data. AT&T and Verizon's thresholds are both at 22GB per month. AT&T's Unlimited Plus offering, which allows full LTE speeds, is even pricier at an additional $30 per line for the first two lines. But the networks have forced the terminology on us, to the point that any plan that doesn't cut you off when you hit a limit is "unlimited".
It's good to see that T-Mobile is continuing to be a disruptive force in the United States telecommunications industry.