Earlier quoted context omitted.
Young developers (as one myself), tend to be overly focused on what makes them attractive as a developer. Kinda like an overly insecure teenager. So they pounce on any framework or tech that makes them desirable to an employer. Rails isn't hot, so it won't get them a job so they won't learn it.
That's flat out wrong. As a Rails developer, I have a weekly stream of recruiters trying to get my attention.
I know 2 COBOL programmers who are being paid a ton of money because of critical banking systems running it and candidates are hard to find.