There is no real reason why high point players should be prohibited from sitting at low point tables. A player could make the top 100 if they played just 100's but the statistical probability of that actually happening is insignificant. Furthermore, players will typically prefer higher risk tables if they are competitive. Limiting also operates under the assumption that there will not be good competition at the lower tables, which is untrue; although competition should get more fierce the higher the risk. Finally, its nice to play with low point friends without having to use an alt.