A few reasons I think. One is that the vast majority of internet content is in English so there's simply less to be bombarded with.

Other reasons are cultural, Asian countries tending to be more homogeneous and still holding onto stronger family and local ties than the west, their societies are older than the west and have less transplants , though with modern Urbanization this is slowly becoming more like the west. There also tends to be a lot of social stigma towards acting out in public still which is far different than the west.

I think other reasons come down to technological barriers towards the use of Asian languages in computers slowed down public adoption of a lot of technology or at least forced it down different paths. The data requirements needed to encode Chinese characters for example are far more robust than alphanumeric and early computers were very unwieldy for the average person.

Finally I think that the political situations themselves are vastly different. If you can read Asian languages well you can go online and see many of the same kind of toxic twitter threads you'll see anywhere, oftentimes they are far more inflammatory than what you'll see in English. But this is because most people don't take them very seriously.

China has very tight controls on all internet use and will shut down anything it thinks is going to cause an uproar. Other countries tend to have more freedom of speech but conditions are generally as such that most young people don't get involved in politics.

I think the kind of extreme twitter polarization that you get in the US is largely a factor of the US bi-partisan political machine which is a fairly unique configuration amongst the world's countries. This spreads into other countries I think via the ubiquitous nature of English and the US population totally dominating the Anglosphere. Even if you combine all the populations of Canada Australia and the UK you don't even reach half the US population.

Asia is a different environment politically and socially. Chinese social media certainly has the population for the same factors to really take hold but the Chinese government is easily one of the more censorious in the world so it's more or less impossible for social media trends to take shape without coming under direct scrutiny and facing shutdowns should they proceed in a direction the ruling class wishes to squelch.

The other languages simply lack the population and geographic distribution to really be as relevant as major languages like English or Spanish. Chinese and Hindi are the only Asian languages that come anywhere close. I suppose Arabic should be considered as well but it tends to be mutually unintelligible in different regions and is largely used in the same way Latin was used in Medieval Europe, used by the religious bodies but not the common tongue of the people.