The power continuum of the developers wielding those languages isn't mentioned as much, but clearly is an important issue. I've worked in blub languages with developers who are so many levels above me they are not even speaking the same language anymore. The problems they are trying to solve take for granted all I know, all I struggle with, and all I still haven't even learned yet.
The more I "level up" in development, the more I'm convinced there is not enough attention paid to how to really advance through those levels. Right now I'm three languages into "Teach Yourself Programming in Ten Years", http://norvig.com/21-days.html but what about after that? And that is just one man's brief and not well-explained suggestions.
I'd love to see other developer's suggestions for how they advanced past that.
The biggest issue though is it's almost impossible to know your skill relative to the rest of the development world. We can't just time ourselves writing a script, like in the olympics, so almost all of us have a hugely overinflated or underinflated sense of our own skill. Everyone has hundreds of anecdotes proving their value over those who by any metric would be our betters (years of experience, languages mastered, formal education, etc).
I'm reminded of when I was a brand new developer in my first job, how pleased with myself I was at my commit messages, compared to my officemate. Sure, he worked on patching a financial aid system written in three languages, two of which I'd never even seen, and I only wrote sql queries to be run by hand, but I knew what made me better: commit messages.
This confirmation bias is one reason I like pair programming, especially between two partners of different levels. Suddenly the lower gets to be faced with someone who gets done ask the same things and avoids this problem and that problem. They see their relative place, and can aspire for levels greater, which before would never have occurred to them even existed.