There are few benefits of having an overseas assistant. The main advantage is cost.
It’s much cheaper. Secondly, the cost of living in other countries is much less than in USA so you can get a better professional with university degree striving to work at a lower salary instead of a low-skilled employee for the even bigger amount of money.
Thirdly, most tasks as, for example, researches or landing page creation, don't need specific knowledge. Soft skills are way more important and this is something we look for when choosing our PAs.
Yes, some of the tasks like calls may require extensive knowledge in English. Our PAs are fluent in English. Yes, they may have an accent, but the US is a country of immigrants, so most people are used to such things. Communication skills are much more important.
Finally, ask yourself: Do you really have tasks that really require American workforce living in your time zone? We doubt so.