IMHO Google has been in decline since ~2010 or so, but it's only recently that the dive in quality became very noticeable. Try searching for anything even mildly technical outside of software, and you are presented with pages upon pages of completely irrelevant SEO spam. Automotive repair manuals (for very old cars) are one example; it used to be that you could easily find a link to a PDF, and the results were otherw…
I think this applies to many large companies. The ones that do best, the ones that are the greatest public benefit, seem to be governed by a strong leader who stays at the helm. As soon as the people at the top change, you get jostling and unclear leadership, and power gets diffused. You get emergent behavior - lots of internal and external competing for power and interests - and the ability to say "no" or "this suck…
Not necessarily. When you find yourself with beancounters and MBAs at the helm, they for sure will optimize the company to outcompete others. Such companies will eventually die from the rot, but not before they drag down the entire industry they're operating in.