LLMs are not the root cause here, they're just an accelerant. This was always inevitable with the progression of globalisation. Even before the internet, kids were watching Disney cartoons across the world (to be fair, often dubbed in the local language, but still an example of how global culture had been narrowing.) Perhaps this wasn't felt as strongly by those in the US quite as quickly as the rest of the world, because their culture just happened to be the source for many of these common elements.

There are always trade-offs. Globalisation has too many benefits for most to want to go back. It is up to us to intentionally cultivate our cultural uniqueness, but I'm not sure the corporate environment was ever the right place to do so, given it was already constrained by rules and etiquette, and motivated by a desire to encourage universal communication styles. Instead we have to take it upon our selves, in a very intentional way outside the corporate setting, to cultivate our own unique cultural expressions to thrive. Failure to do so either directly, or by proxy, means cultural extinction, as has been the case of many cultures that have passed before.