I don't know about the rest of the world but Canada has rules as to percentages for investment other than Canadian so in my opinion you would been locking out everyone else. Perhaps I am way out in left field or totally wrong, and frankly I don't really care because I have as many shares as I need. But if I had no shares and wanted to buy I would be restricted to a certain percentage of shares as per Canadian rules
Excellent post. Some firms charge an international fee for US investors to purchase these stocks. I know firsthand trading thru Vanguard until a few years ago.