Honestly just working on something without an existing user base makes a huge difference.
There's a certain amount of institutional crud that's just crud, but most of it exists because once you are successful, you can lose what you have more easily than gaining something new.
Millions or billions of people use the major products FAANGs provide. They might get more users if they make these products better, and boy howdy are there a thousand ambitious devs, PMs, and managers trying, but they'll also lose millions of users if they make them worse. Hell, they'll lose millions of users if they make them different, regardless of whether it is better or worse.
90% of institutional crud is "how can we not piss off the billion people who are happily using our products and giving us money, either directly or indirectly?". Users hate it when our product breaks, so we're going to have excruciating review and approval processes to submit code changes, style guides and minimum test coverage and an entire campus devoted to monitoring for problems. Users hate it when their personal data gets leaked or abused, so we're going to set up razor wire and require devs to go on a quest for mystical artifacts before they can do anything with it. Users hate it when the site changes so we're going to require a dissertation in the form of a sonnet explaining why the color of the buttons should change, and then six months of live experiments to be sure.
90% of what you hate as a user about big companies is the result of them "acting like a startup" and radically redesigning UIs or changing the core functionality of a product or breaking existing functionality to add new or just developing a new product out of nowhere and presenting it to you like you should care.