One of the things I hear often said, and something I subscribe to as well, is the idea that a lot of technical knowledge in the world of IT has a very short shelf life. When interviewing candidates, we really tend to focus on what they've done in the last few years when considering their technical skill sets. As a practitioner, I start feeling a little stale on my knowledge if I don't touch an area of IT for awhile. That's not to say that anything beyond 3 years of experience is worthless though, because the value of good experience isn't really in technical skill. What you should be paying those IT greybeards for is their presumed ability to see patterns and discern bad decisions before they are made. That's a skill of it's own, and a muscle that needs to get some exercise by being allowed the opportunity to voice an opinion and have it feel valued.
A recent real-life example that recently occurred illustrates this well: