Correct. However, for some reason, the internet on my iPad is slower vis-a-vis my MacBook Air when tethered to my iPhone. With the legacy plan, I can connect BOTH the lappy and the iPad at the same plan. With the new plan, this has not been possible. One user's experience.
They were able to lock down iPhones, it has always been one device limit on hotspot but wasn't really enforced on the old system. I have the ability to hotspot multiple devices on my android phone but rarely do so since hotspot is limited to 5Mbps speed.
I am unsure but think I read they are limiting streaming such as Netflix to 2Mbps speeds and not sure if that is on hotspot also.