Indeed, and there are edge cases, like Facebook, or Google, or whatever. The edge cases are gigantic databases that are accessed in certain specific way.
It's true that many people attempt to prematurely optimize by using Cassandra first instead of something they are already familiar with. However, when faced with some of the pains of growing an RDMBS beyond what a single box can handle, it's worth it to consider your other options. Keep in mind that if it's easy to store and make use of a huge pile of data, you're more tempted to gather that data in the first place, where 10 years ago it might have been prohibitively expensive or difficult.
There are probably less edge cases than actual NoSQL codebases, which is pretty surreal. There are more actual products then the number of people who need the products. And 99.99% of the people playing with them don't need them at all.
I can assure you that you're incorrect, but since you don't have any data to back this up, I won't bother either.
The real joke is people using them in ways that are actually slower than any RDBMS, but they think it's 'easier', usually because they never bothered to learn how JOINs work, and don't understand that it's perfectly fine to make a dozen SQL queries on a web page...that's what indexes are for.
Yes, only knuckle-dragging imbeciles are interested in new systems... *sigh*. This is an often-touted piece of flamebait that has little basis in reality. Some of the largest Cassandra users are companies who already have extensive experience scaling MySQL and other RDMBS.
While some might find that document stores like MongoDB are "easier" and use it for that reason, Cassandra has a reputation for being difficult to get started with; the reason it gets used nevertheless is because the benefits outweigh the steep learning curve.