that would be counter productive as they won't have enough man power to find all the bugs in order to fix them. whatever your beliefs about people's motivations, open beta testing has been proven to work.
as a closed and open beta tester for a number of games, i can tell you many are enthusiastic about helping the developer polish the game. even if they're a minority, they contribute greatly to the quality of the finished product. just a dozen real testers would be enough. that's why you invite a large number of people to increase the chances of there being serious testers among them.
i have personally witnessed crucial bugs being squashed in many closed beta forums.