Google's promotion and incentive structure is built around launching products. This will launch, putter along for a couple of years and then get shuttered unless it's a surprise success.
You say that like it's a bad thing, but isn't that effectively how Silicon Valley as a whole operates? Most startups putter along for a few years before running out of money and getting shuttered. A couple become surprise successes and take off.
Google is effectively just a single corporation acting like a hive of startups.
Honestly there's a really good blog post/article waiting to be written grouping and classifying shuttered google projects into groups based on purposes, because for a lot of them, they aren't created to be successes or make money, but for other business reasons, legal precedents, creating competition or disrupting a particular business segment, etc.
I'll wait until my mom tells me about it.