The implication that someone couldn't keep up with a relatively new things-- in your case vague example something they even encountered a few years earlier-- is

The implication that someone couldn't keep up with a relatively new things-- in your case vague example something they even encountered a few years earlier-- is pretty much the definition of ageism. Anyone who decides to keep their professional skills current will do just fine whether they're 5 years out of school or 40 years out of school. If someone doesn't keep current & is 5 years out of date on their skills, there's not a lot of difference between a 30 year old and a 60 year old that are equally 5 years out of date. Though the 60 year old might have decades more of experience working in their advantage, so maybe the two aren't equal.