Yeah, it seems closer to a "tragedy of the commons" kind of situation. Where a few users deplete a shared resource affecting everyone else.
Unlimited means that you don’t have a set quota and as long as your usage doesn’t cross over into genuine abuse of the service that you don’t have to worry about it. If you cat /dev/random into your unlimited storage provider 24/7/365 you can’t really be surprised when they ban you.
Storing large amounts of random data merely to waste space might qualify as abuse. But that is a) a strawman as far as I can tell and b) it isn't always possible to tell apart random and encrypted/compressed data apart anyway.
Just admit all people want is to be able to ride the gullibility of people who aren't as picky about language as the people who actually give a crap about clear communication. What businesses want to sell is a conditionally vague statistically multiplexed service level, and I'm willing to bet most don't even go out of the way to let the User know what they're overall footprint within the scope of the entire system is, which is info they'd need to manage usage patterns themselves. It's the hallmark of manipulative language.