I think the acronym Google always misses out on is KISS (Keep it Simple Stupid) because no one there is "stupid." If you only hire geniuses, no one wants to write documentation or do things the boring/easy way that would create more maintainable software.

Instead everyone there has to use the latest framework or best practices, then re-engineer things to prove they deserve their top-performer salary.

I think the first Google Hangouts was written in Angular 1? Code rot from frameworks like that will ensure the product will die in 5 years at a company like Google. Everyone at Google is a "top-performer" so they want to use the latest development tools and shiny things and no one wants to upgrade/maintain 5 year old code written in an old framework.

I think a lot of other companies get around this by hiring less than top performers. Those types of coders will maintain legacy systems because they don't have as much pride. So I think it's mainly a problem that Google has a culture of tech elitism, instead of a culture that focuses on user satisfaction.