One of Google Search’s oldest and best-known features, cache links, are being retired. Best known by the “Cached” button, those are a snapshot of a web page the last time Google indexed it. However, according to Google, they’re no longer required.
“It was meant for helping people access pages when way back, you often couldn’t depend on a page loading,” Google’s Danny Sullivan wrote. “These days, things have greatly improved. So, it was decided to retire it.”
My guess is that a cached page is just a byproduct when the page is indexed by the crawler. The need a local copy to parse text, links etc. and see the difference to the previous page.