As a hiring manager who is also 100% responsible for the content of the job ad (this is not always the case, as other answers have noted), "years of experience" is meaningful to me. However, exact matches for years of experience is not so meaningful to me. That is not the case for strict, by-the-book HR screening processes and resume matching, which is still quite prevalent in many industries.
Taking a look at your example -- "Minimum 5 years experience with xyz technology in a commercial role" -- if I had written this (which I wouldn't, exactly), what I would care about is the plural of years, the specific technology, and the "commercial" part. What that says is "we want someone who is not just out of school, who uses or has used the same technology stack we do, and who has worked in a team, in a production environment, and in general knows what that entails."
The use of "5" instead of "3" in terms of years of experience says to me they do want someone with at least a few years under their belt -- if you're just out of school or internship, that's not really what they want. If you see "3" in terms of years of experience, if you're good and professional, but only have a solid year of work, they could very well take a look at you. In general, there's a difference between 3, and 5, and 7 in terms of expectations of skill level, teamwork, knowledge of processes, responsibility levels, and so on, even if the numbers don't precisely line up.
As an example, here is a "requirements" statement in one of my job ads:
A solid understanding of the Ruby language and the Rails framework,
and at least three years working with it in a professional environment
(if you have less experience with Ruby but have been working
professionally with other languages and can make a good case for your
skills, do it!)
What I'm looking for is someone not just out of school, who has been working with Ruby and Rails for more than a year, in a team environment, in a production environment, and who doesn't need a lot of hand-holding. Recognizing that people switch languages either for fun, profit, or otherwise, I'm also quite happy to see resumes from people who have (for example) worked in Java professionally and then switched, or PHP professionally and then switched, or (insert other languages here). But even then, if they've just switched, that's probably not someone I'd rate terribly highly -- they have to make good case for their skills (which for me comes out in their take-home assignment after a phone screen).
So yes, I genuinely look for some reasonable number of years close to what I ask for in a job ad, but I also look at all the other factors involved. Four solid years of work in a single language when I'm looking for 5? I'll probably interview you. Only 2? Probably not. Three years in one language and a switch to another? Probably would make it through my first cut, but I'd want to read something interesting about it in your cover letter.