Unlike other cuts of meat, there are no cooking commandments etched in stone regarding steak, only the means to certain ends. How you handle steak comes down to what you intend to do with it.
Caramelization, Flavor and Thickening
Recipes for cubed steak and beef stew often call for browning the meat before adding stock. Dredging the meat in flour, then frying it expedites caramelizing, the oxidization of natural sugars present in the flour. The flour also serves as a thickening agent. The dredging stage isn't entirely necessary, and you still can produce a respectable stew or cubed steak without it. So if you're frying steak, namely chuck, to make any of the above, you can omit the flour-dredging step.
Country-Fried or Chicken-Fried Steak
If your intention is to fry a steak as for country-fried or chicken-fried, you definitely need flour. The flour serves as the first layer in a series of starchy layers that when fried form the crispy, browned crust. Dredging the steak in flour reduces surface moisture on the meat, allowing wet ingredients such as egg and batter to adhere and form a light paste. It's rather difficult to achieve this crust without a flour-dredge step. If gluten is a concern, use alternatives to all-purpose flour, such as garbanzo flour, fava flour or tapioca flour. It's also quite acceptable to fry a plain steak lightly seasoned in a tablespoon of olive or canola oil. The sugars present in the meat caramelize, forming a golden, crispy exterior.