Author mentions Clojure a few times as an example of shiny-thing. Ironically, it's one of the few languages that I can reliably do in the browser, on the backend (on real servers or say, Lambdas), and build native binaries for -- which addresses the later "many tools" problem better than a "boring" programming language like Ruby. Unless you don't care about frontend code I guess :-) (Overall this talk is fine! I thin…
One of the places I'd say they are appropriate are in places where you have some problem where some "shiny-thing" stands head and shoulders above the "boring technology" in some particular and you can ram home those advantages well enough to overcome the other issues. For instance, if you've got a server where you're going to have several thousand clients opening a socket connection and babbling away at each other in some custom manner, starting with Erlang/Elixir is quite possibly a very good idea, because none of the "boring" tech is anywhere near as good at that, even today.
But I do agree that when doing the cost/benefit analyses of these choices, far too many developers plop an unprofessional amount of weight on the "benefit" side that amounts to "it's fun to play with the pretty-shiny". (I'm still recovering from some old "NoSQL" decisions made in a context where a relational database would have been more than adequate, at most backed by something that even at the time was tested like memcached, instead of a combination of what are now completely defunct and semi-defunct databases.)