Data caps suck. They don't address the problems that exist in any meaningful way, and are simply a method to get money from your pocket into someone else's bigger, fancier, designer pants pockets. All of us know this on some level, but if you're curious why and how they aren't the safety net carriers and providers claim them to be, you'll want to watch this video. It does a fine job explaining TCP/IP network congestion, "power users" that hog bandwidth, streaming services, and why none of that is addressed by capping a users data.
This won't likely change anything, but at least now we can be a bit better informed the next time someone on the other side of a counter tries to talk you into a higher priced data plan.