A classic French way of browning meat offers 2 benefits, none of which include sealing in the juices for stewed meat.
As the meat is stewed over a period of time the juices escape into the cooking liquor anyway, the benefits of browning meat dusted in seasoned flour are:-
1. a nutty (Noisette) flavour will enhance the depth and character of your stew.
2. the browned flour will also add a thickness to the liquor of your stew coating all those wonderful slow cooked ingredients.
If you are cooking meat that is not stewed for example a chicken breast, sealing the meat will help retain the juices inside.