The inventions are to keep the talent stream coming ... to work on ads.
The inventions are the small tax they pay to pretend to candidates that they could work on inventions when the vast majority of them will be "allocated" to ads.
It's also Google licking the cookie. They maintain a moat around ads by doing just enough to threaten to destroy anyone that gets close to their ecosystem.
Facebook survived because G+ product vision was so out of touch with reality and FB were not part of the anti-compete hiring nonsense so that they managed to poach a lot of good people.
I doubt they did anything like that intentionally. My impression in my time there was they were constantly cargo-culting themselves. X obviously works, so keep doing X, even if it doesn't look like it makes any sense. And X was absolutely everything.
You need Shiny Inventions so you can divert the talent stream away from your competitors, more than to actually work on the ads.
I'm sure there's some Shiny Invention Corner in the ads business -- let's call it "AI" -- and some of the top people can be motivated to work there.
But isn't the ads business by its very firehose-of-money nature something that will get on fine with that average level of talent that is sufficiently motivated by cash and doesn't need Inventions?
And isn't the top talent able to make the same money doing interesting things elsewhere? (I keep hearing this is happening with AI, but I hear it on Xwitter so who knows.)
The inventions are the small tax they pay to pretend to candidates that they could work on inventions when the vast majority of them will be "allocated" to ads.