What is the purpose of the light coating of flour in a three-step bound breading? I've always understood "bound breading" to refer to a three-step process, performed with chicken or other meats that have been portioned and patted dry:


Dredge through (seasoned) flour and shake off the excess;
Coat with beaten egg, slightly thinned (with water, milk, etc.);
Coat with an even layer of desired breading (crumbs, more seasoned flour, etc).


Recently, I came across this web page which describes bound breading as a two-step process, excluding the first step of dredging in flour. It occurred to me that, although I've always done bound breading this way, it seems like the thin layer of flour between the meat and the egg mixture would actually work against the breading sticking firmly to the meat. And yet, this is the way a bound breading is done in all the recipes and cookbooks I've encountered previously.

What is the purpose of that first light coating of flour, structurally speaking? Obviously if you use seasoned flour, you're adding seasoning; but does it really make the breading stick any better through the cooking process?
The flour as the first dredging step does help the rest of the breading stick. Think traction. It gives the egg something to hold on to, which then holds on to the breadcrumbs. You're right, the vast majority of recipes that call for this kind of breading call for a three step process. That's because it works better. I've done it with and without the initial flour dredge. With is better. Considerably.