It would seem like it. In terms of innovative research, it doesn’t seem like, say, Google Research is so much more productive than your average prestigious research university (albeit possessing perhaps a different set of focus areas). Similarly, when it comes to improvements on technical infrastructure, it seems Google plays a large role, but not an exceptionally large one, which makes sense by virtue of their massive deployments and having the capital to hire good engineers. Still, this doesn’t seem so outsized—Meltdown/Spectre weren’t discovered solely by Google, for example.

On the other hand, when it comes to product innovation, it definitely seems like the bulk of it happens, as you said, outside titans. Again picking on Google (sorry), V8, Google Docs, Google Maps, YouTube, and Android were all acquisitions! And though Google acquiring them might certainly have given them large amounts of resources to expand (e.g. subsidizing YouTube), there is definitely the question of stifling innovation and competition. Consider TinEye, who first published reverse image search; later Google just poured engineers onto their own reverse image search platform and copied it.

I think you can see the same dynamic with Facebook copying Snapchat features. It doesn’t seem like a healthy market.

EDIT: V8 might be better characterized as the product of an acquihire, actually. It might not fit with the rest of the list, which were all literally acquisitions of products developed outside Google.