[DrJokepu]

I don't know about your specific case but it's typically not the presence old technologies that devalue a resume; it's their presence AND the lack of new technologies that does that, because it indicates that the candidate doesn't think it's important to keep himself up to date regarding the latest developments in his profession, which is a huge red flag.

Just this week we've interviewed a lady for a development position who had a very long career and had experience with not just old technologies such as, I don't know, Delphi, but she taught herself new things as well such as ASP.NET MVC and Node. She is a mother of two yet she has managed to find time to keep her skills up-to-date. Obviously we have offered her a senior position pretty much immediately.

[fsk]

The problem is that there's 100 new things, and it's hard to tell what's going to last and what's just a fad.

Also, once you have a job using X, there isn't much opportunity to get work experience in Y.

I've also have several recruiters say "Learning stuff on your own doesn't count. You need actual work experience in Y for employers to value it." That's hard when you have a job where they only use (somewhat-obsolete) X.