Yeah, sadly, that's a common problem in software development. People often use technologies on projects because their resume needs them, not because the project benefits from them.
I wonder what our technology choices would look like if this weren't the case. In other words, suppose someone said to you "you'll be responsible for these software applications for the next 10 years" vs "you'll need to find a new job every 2-3 years for the next 10 years." Would we adopt and apply new technologies this aggressively? Would we be changing javascript frameworks constantly? Would we necessarily be using them at all, vs a wait and see approach? (btw, yes, depending on the project sometimes we would use them, but my guess is that we would far less often).
It's happened a bunch of times in my career by now. Currently, I think our huge over-application of technology is in the realm of constantly evolving front end javascript frameworks. I still believe, firmly, that most smallish apps would be better handled through an integrated framework like rails or Django, with a bit of judiciously applied javascript when necessary. Or, perhaps, even no framework at all.
But unfortunately, that doesn't get you jobs. Almost all the rails jobs out there now require expertise in Ember, React, etc. So the truth is, it's rational to add these things to your current rails project even if you don't think the trade-off is quite worth it.
Just to be clear, yeah, sometimes it is worth it. I look at it this way - for a while there, most land animals had exoskeletons, even some fairly large ones. Then, endoskeletons came along, and it turned out that to scale up to be a giant land animal, you needed an endoskeleton. Some of the larger animals with exoskeletons started to go extinct, as the more scalable endoskeletons drove them out of their ecological niches.
Here's the part that they don't cover on the nature channel - recruiters started to ask giant centipedes if they had any experience with endoskeleton. Senior architects and technology directs started insisting that fleas, ticks, and flying gnats have endoskeletons, because they attended a conference that told them that if you want to to wooly mammoth size, you need endoskeleton.
Meanwhile, the creators of endoskeleton frameworks are (rightly) all like, "Don't put this on me, I never said a gnat should have an endoskeleton".
Oh as for machine learning... yeah, I suppose there may be some use of spark, map reduce, Hadoop, and so forth that exists to gain experience with these technologies rather than because they're needed. That definitely happened with some of the noSql stuff. But honestly, the unnecessary churn on the back end/data science side pales in comparison to what happens out there in the web world.