Man these language debates are so irrelevant when you're talking about web apps. I honestly couldn't give a shit what I use, it takes like 2 weeks max to adjust to a new framework/language.
Most people I know and work with feel similarly...and it's not some amateur speaking here.
For a recent developer - no, it’s impossible. For anyone who wrote code for 10+ years, picking up a new language and framework is typically piece of cake (I’d say 80 hours is more than enough).
Complexity comes from learning a new domain - a web developer can’t learn mobile, game engine, or HFT development in two weeks, but that doesn’t have to to do with languages or frameworks.
I'm 49 years old, and I've been programming since I was 10, on a Vic 20. I've been doing web development for 20 years, from Frontpage to PHP to Rails to .NET to Java. Picking up .NET wasn't terrible, but I've been at the Java/Grails/Spring/Angular stuff for MONTHS, and I'm just barely getting off the ground. I guess I'm just old and/or stupid.
I get you can't escape Angular (and friends) if you are doing front end, but why not just stick to 2 things on the backend? php and java, ruby and .net or whatever. I just don't see the point in doing Grails, Rails, Spring, Laravel, Node etc etc instead of mastering 1-3 technologies really well.
I was told, essentially, that Rails is still too new and scary to be considered secure and mature and ready for enterprise use, and that I had to use either .NET or Java. There's another half of this project that's already written in pure client/server Java, so that's what I chose. If I had it to do over again, I would have chosen .NET.
Most people I know and work with feel similarly...and it's not some amateur speaking here.