I think it comes down to how they handle success at a smaller scale and tend to prioritize for their higher value experiments. I think the better example, on the other side of Google would be Apple, where almost all priority is in the Phone first, Tablet second, everything else after.
For google, you have one line of business than generates billions in revenue and another that generates a few million in profit, in the larger company, it's not likely to gain traction, where in another company it might be larger than the rest of the company.
> I think the better example ... would be Apple, where almost all priority is in the Phone first, Tablet second, everything else after.
To be fair, the iPhone has been an earth shattering success that created multiple brand new markets (e.g. App store, Apple Pay) and propelled Apple to become the first trillion dollar company in history and the most valuable brand in the world. It's difficult to convincingly make the case not to prioritize a product line like that above others.
They have enough funding they could easily have spun of both MacOS and the Macintosh hardware into separate sub-companies or reorganized the organization structure a number of ways not to let things stagnate for over half a decade. MacOS and even the hardware largely feel like how IE6 was for the longest time.
For google, you have one line of business than generates billions in revenue and another that generates a few million in profit, in the larger company, it's not likely to gain traction, where in another company it might be larger than the rest of the company.