Languages DO matter. Language features matter, too. Even syntax matters, although not that much.
It's easy to get trapped in "languages don't matter" attitude if you know a couple languages. The perspective changes drastically with mastery - being able to use a language to its fullest, as opposed to just using it - and with dozens more of learned languages.
A language is your baseline, a starting point for building things. How you build API, how you interact with outside world, how you accomplish common tasks depends on a language and language features. And it gets even more important as you climb the abstraction ladder. For example, at language level Scheme offers call/cc. You may say it doesn't matter, as it's just a language feature. But take a look at Racket continuation-based web server - it's an impressive piece of work which solves a certain problem really well and is almost impossible to implement in some other languages (you don't need continuations specifically to implement this, there are other features which would enable it). At a language level Lua offers coroutines, which in itself is not very impressive. But take a look at OpenResty: you can write code which looks perfectly normal and synchronous (no callback etc.) while still fitting inside of async by nature Nginx.
Anyway, thing you mention, like APIs, do matter too, but language features are equally important. Don't dismiss them because you superficially know a few languages; rather learn some of them in depth and build real world things with them and I'm 97% sure you'll see how language features matter.
I think you're missing George's point. Languages don't matter in isolation. It's the language plus the libraries plus the rest of the ecosystem, which he's calling the "platform".
If you have this language with these great features, but it has lousy libraries and therefore you have to write a bunch more stuff yourself, you need to weigh that against the great features when deciding whether to use that language. Just having the great features isn't enough. (In fact, this is a big part of how Java conquered a big chunk of the world. As a language, it's kind of a yawn. But the library is like Barbie - it has everything.)
I completely agree. As I wrote, libraries and other features of a platform do matter and of course you need to take those into account when deciding which language to use. It's always very specific to a given situation though, for example lack of "batteries included" libraries may not be a concern when choosing language to embed in your app (like Lua). But in general great language features and great platform features (for example working package manager) are both very important factors that you need to take into account when deciding on language(s) for your project.
Bullshit.
Languages DO matter. Language features matter, too. Even syntax matters, although not that much.
It's easy to get trapped in "languages don't matter" attitude if you know a couple languages. The perspective changes drastically with mastery - being able to use a language to its fullest, as opposed to just using it - and with dozens more of learned languages.
A language is your baseline, a starting point for building things. How you build API, how you interact with outside world, how you accomplish common tasks depends on a language and language features. And it gets even more important as you climb the abstraction ladder. For example, at language level Scheme offers call/cc. You may say it doesn't matter, as it's just a language feature. But take a look at Racket continuation-based web server - it's an impressive piece of work which solves a certain problem really well and is almost impossible to implement in some other languages (you don't need continuations specifically to implement this, there are other features which would enable it). At a language level Lua offers coroutines, which in itself is not very impressive. But take a look at OpenResty: you can write code which looks perfectly normal and synchronous (no callback etc.) while still fitting inside of async by nature Nginx.
Anyway, thing you mention, like APIs, do matter too, but language features are equally important. Don't dismiss them because you superficially know a few languages; rather learn some of them in depth and build real world things with them and I'm 97% sure you'll see how language features matter.