It's the same in every other stack/programing language/technology when you go through the default channels of HR/recruiters.
It's not that competent engineers can't become quickly productive in a new/stack language, it's that business don't understand that and/or don't want to risk it with switchers, and so prioritize hiring only those already experienced in that stack, creating employment bottlenecks where there's simultaneously a shortage and enough people willing to switch.
Same when talking to recruiters: "oh you only have experience in X (which is similar to Y), sorry but the hiring manager said (s)he wants someone with at least 3 years experience in Y".
Your only escape is having a solid network so you can push your resume directly to hiring managers who understand technology and your adaptability, and this way bypass the hiring shit-show.
C’mon. HR doesn’t have a clue of what they’re asking for. Anyone with a little of experience in the IT industry knows that:
1. You’ll need to put whatever is needed in your CV to pass through HR
2. You can explain yourself to the actual tech people who interview you in the next stage. For example, if you know Ruby and RoR, but there’s an excellent opportunity to work in a cool product for a company that does Python and Django, well, apply! Obviously you’ll spend a couple of days with Python and Django and notice the similarities and differences with Ruby and RoR. You will add to your CV the keywords Python and Django and you’ll get pass HR (if HR asks you about your experience with such tech stack you can always say that, indeed, I have plenty of experience with MVC web frameworks and blah blah blah). When you pass to the next stage of the interview and get to talk to real engineers, then you can explain that you have many years of experience working with RoR and that learning Django will be a pleasure.
