Sometimes all the info you will have to start off with is their stack size, screen name and number of tables. In this case it's pretty good info. We want to use all the info we have available to us and then as we accumulate more info we prioritize the info available to us and determine how beneficial each piece of info is. If you only know three things about somebody then each piece is valuable. As we learn more such as tendencies, aggression etc. things like screen name and number of tables become less valuable in comparison.

Over all there are plenty of poor mutli-tablers just as there are many great single talbe players.