You're unbelievable.

Have you considered the possibility that you are just wrong? Your 'uncontroversial and rather obvious historical fact' is neither uncontroversial nor is it obvious.

That's why we have a 32 page article on the subject on Wikipedia:

https://en.wikipedia.org/wiki/Political_status_of_Taiwan

And it is one of the most heavily brigaded pages there. With edit wars going back as long as the page exists.

As well as articles like this:

https://www.justsecurity.org/87486/deterrence-lawfare-to-sav...

There is only one country where your 'historical fact' is seen as true, and it isn't Taiwan. And that is why China is threatening to invade, and why you yourself use Taiwan without further qualification right after 'South Korea':

https://news.ycombinator.com/item?id=46478045

The 'one China' term itself is overloaded, depending on who you ask (Chinese, Taiwanese) you get different answers.

Taiwan is an independent country, if not de jure then de facto. That China is a much larger and much more dangerous country is the only reason everybody tiptoes around this.