You have a group of enthusiastic founders who make it big through smarts, passion and dedication and after a couple of decades, they retire, and the company is now mostly formed of people who are in just to cash in on the money and fame from having that brand name on their resume as people who are as smart, passionate and dedicated as the original founders were would most likely work on their own idea rather than said famous company.
On the tech circles online Google is known for being the place where you grind leet-code to get in so you can make big $ and coast (rest and vest), not break your back working on fancy world changing ideas. The latter is for start-ups.
Apple was ahead of the game too as they had the visionary Steve Jobs at the helm, while now, sure their stock is as high as ever and their M1 macs are great but you don't really see people queuing up for days in front of their shops anymore since their post-Jobs strategy has been less about disruptive innovation and more about entrenching and expanding their existing positions by leveraging their supply chain prowess.