Here is the secret. Whenever someone brings up that US has a "DEFACTO EMBASSY" in Taiwan, just point to the US Consulates in non-sovereign territories that is part of China, like US consulates in Hong Kong and Macau.
They do exactly the same function as the AIT. The HK and Macau consulates all do "economic, cultural, and trade exchanges" and do visa-processing and citizenship services, exactly like the one in AIT in Taiwan.
But you can see, Hong Kong and Macau are clearly part of China right? You can have US consulates in non-sovereign territories. Taiwan is a non-sovereign territory with defacto consulate just like HK and Macau has US consulates.
Source: HK-American dual citizenship.
