Every day SEO-tards come up with new ways to try and cheat, gaming the system. That's all most of what the so called SEO "experts" do, particularly those who 'specialize' in it, or worse, have entire companies that do SEO as their only business -- they try and cheat, using sneaky tricks and outright lies to basically rip off site owners who don't know any better. It's a giant bundle of lies, fictions and marketing trickery -- sadly so many buy into it that many have deluded themselves into the belief that such garbage actually serves a legitimate purpose other than ripping off the ignorant, naive and innocent. There's a reason I consider them to be little more than predators.
So as the scam artists and jackasses who seem to think their goofy tricks and fantasy-land bull are worth anyone's time come up with new methods of trying to trick search engines into listing their garbage first, Google and other search engines have to find a way to slap them down.
Hence, updates. It's Google's way of kicking the hoodoo-voodoo snake oil doctors in the crotch.