To make them have to go back to coding academy school in two years?
So that they maintain legacy codebases and don't touch the new shiny features the experienced engineers are working on until they get their training wheels off?
Because there is actual demand for ruby on rails despite all the hate and sunsetting of rails I see on HN?
Also, and I'd love to see actual demographics on this but I know it's impossible, while lots of posters on HN/proggit/whatever are professionals, a lot of them are also high school or college students that are still coming at it from a hobbyist perspective (i.e., focused on what's new and exciting rather than engaged in the relatively boring world of getting paid to solve other people's problems). For that matter, a lot of the professionals approach their work from a hobbyist perspective (not necessarily a good thing for their customers).
I don't mean to sound like I'm down on hobbyists or students at all, just that different people care about different things, and just because most HN posters know a lot about the technologies they post about doesn't mean they know or care about the actual state of the industry (just their corner of it)(that applies to me too of course, we're all like the blind men and the elephant).
Big companies use enterprise Java unless they're stuck with a legacy VB/ASP/Coldfusion stack, with C# less commonly.
Fintech companies use a mix of C# and C++.
Small companies started before ~2010 use PHP, with Rails less commonly.
Small companies started after ~2010 use Rails, with hipster Java (Scala/Groovy/et al) less commonly.
I can only remember offhand seeing one job ad for a company using Sinatra instead of Rails for their Ruby stack.
Chicago, the land the MEAN stack skipped.
1. it's easy to get something up and working, which for a lot of students helps keep them motivated 2. Hartl's Ruby On Rails Tutorial. So far, it's the best book/course on how to get from knowing pretty much nothing to being able to work in a 'modern' dev setting (good editor, git, bitbucket, testing, backend, front-end, etc.). 3. if they want to actually get a job as a junior dev somewhere else, I've found that joining a startup or company that uses Rails is pretty easy. Much easier than jumping into a front-end React/Redux shop, for example.
I do not necessarily intend to use Rails actively with them in their first projects, and for those who can and want to I'll probably have to introduce them to the complexity and horrors of front-end javascript development, but at least with the Rails Tutorial they can get started by themselves and learn some degree of 'best practices'.