Even when the whole IT certifications thing started, it felt like a scam. But then the certification-sellers (and, not to be unduly uncharitable, but all that the vast majority are doing is selling false assurances) did away with "forever" certifications and replaced them with expiring ones. While you can argue that there's validity to skills being "perishable", most of what's certified is "you either know and have internalized the principles or you havent". While specific symptoms and scenarios may evolve, the underlying principles are generally fairly static. That said, a 3-5 year validity window isn't awful, just inconvenient. You drop down to 2 years (the guilty certification-players know who they are) and you've gotten uncomfortably close to doing to certification what has happened with password-expiration policies.
To illustrate, one set of certifications I have has a two year lifetime. Six months before they're due to expire, the certifying authority starts sending out, "you need to re-test to stay certified - do it early and we'll cut you a break on pricing". Here's the thing, though: if I do the early re-test thing, the next chunk of 24 months' validity isn't tacked on to the end of the soon-to-end 24 months. No, it starts the day you're tests are verified as having been passed. So, if I retest early, I've sacrificed up six months of that 24-month validity (i.e., up to 1/3 of that already short validity is pissed away). So, yeah, "I saved money by re-testing early".
It's like, "dear certification sellers: when my logins start getting that 'you've got 14 days till your password expires' thing, my response is generally, 'good to know: I'll change it in 14 days'. Not having stackable re-certification creates the same kind of outcome."
