I may be wrong on this, as I've only worked on one software team, not at Google, but at least on my team I notice the intense pressure to deliver new features, as well as new product managers who are evaluated on their ability to work with developers to ship fast, results in performance becoming a second class citizen without a very senior very technical owner who ruthlessly shuts down features and projects to protect these properties.
I basically agree, but at the same time, companies compete hard over speed and benchmarks, so it’s not like performance isn’t on their radar at all. And yet the bloat problem exists. Maybe they’re focusing too hard on low-level benchmarks (JS execution, 60 FPS rendering, etc) and ignoring overall app performance.
In short, I feel it's more an org problem.