well, if it isn't to be browned the only thing it could do is help with thickening as has been mentioned. even then it is odd. but with browning, the obvious thing is that you then end up browning the flour NOT the meat. for beef, this would be odd. for chicken, you would normally brown the skin because the meat itself tends to get stringy when it is cooked at a temperature that would brown it. so, flouring the chicken would enable you to give it a slight brown color without making it tough and stringy. for beef, browning improves flavor while for chicken i tend to think of it as cosmetic at best.