Big data tools are just one example of distributed systems. I suggested looking into them because there are a lot of open source ones you can play with, not because I think big data isn't a buzzword (though Spark is definitely used a lot in industry).
Crypto is of course a distributed system too (at least, many are) but in practice it's a bit different than anything you'd see in industry because it's trustless.
I agree that they are novel and interesting to learn, but practically speaking, the person's point, is they are over hyped, and honestly since most use cases popping up aren't decentralized or are decentralized, but being regulated by a centralized party, like a government, it seems that they are the most inefficient way to run a distributed system.
Crypto is of course a distributed system too (at least, many are) but in practice it's a bit different than anything you'd see in industry because it's trustless.