5 years of X just says that the job market can sustain some number of requests for candidates that don’t require as much ramp-up time once hired. It doesn’t mean the candidates will be old, in fact looking for highly specialized tech stacks rather than experience in the business domain of the product is a sign of someone looking to hire young.

5 years of experience is basically a 27-28 year old if they started after getting a bachelor's degree. That's not exactly "old".