Decay is silent
A wrong phone number tells you it is wrong the moment you dial it. A wrong job title does not. It sits there looking exactly as authoritative as it did the day you wrote it, and you carry it into a conversation two years later.
Why lists rot faster than you expect
Assume a three year median tenure. After eighteen months, a meaningful share of any list has moved somewhere else, and you have no signal about which share.
The useful response is not a reminder to audit your contacts, because nobody does that. It is a record that can notice on its own when something no longer matches, and say so.