Isn't just about everything? Hypothesis: For any language X, there exist articles claiming either "X is too immature for real-world use" or "X is no longer a good choice for new development".
Ruby on Rails is somewhat of a special case, though.
Early web technologies like CGI, PHP, JSP, ColdFusion, ASP and ASP.NET arose due to real-world needs.
Ruby on Rails, on the other hand, arose mainly due to hype.
From a technological perspective, there really wasn't anything special about Ruby on Rails. Many of us who had been doing web development for some time had already built or used proprietary/in-house frameworks that offered the same functionality, but were written in Perl, Python or Tcl instead.
If it weren't for strong and very loud personalities within the Ruby on Rails community, combined with some very lucky timing with respect to the rise of the so-called "Web 2.0", it likely wouldn't have been seen as "special", and wouldn't have garnered the hype that it did.
Technologies that come out of an environment of hype, rather than solving real problems, tend not to stick around as long. Systems built using technologies that solve real problems continue to be used and maintained. Systems built using technology chosen purely because some manager or executive saw a webcast full of nice-sounding buzzwords tend not to survive very long.
The idea that Rails' popularity came from managers hearing buzzwords doesn't match my recollection of history. Rails' early support came from backend web developers who hated working in enterprise Java frameworks. Ruby on Rails offered them a pleasant and easy-to-jump-into alternative to that environment.
I remember Pythonistas at the time raised similar complaints about how Python already had all this stuff — but the thing is, Rails did a nice job of packaging it up in a way that was easy for disaffected Java jockeys to get into and start having fun, while the Python approach at the time was more along the lines of "take this thing and that thing — or maybe one of these five other things, we can't decide — then make this other piece yourself and stick them together with chewing gum."
Rails did come to prominence largely through social channels rather than technical superiority, but it wasn't a marketing-driven hype train targeted at nontechnical managers — it appealed to hackers who wanted to have fun but did not already have a homebrew Perl stack at the ready.
