ASP.NET MVC ActionFilterAttribute inject value before model binding

I have found a way to achieve it.

public class ModelBinder : DefaultModelBinder
{
    protected override void OnModelUpdated(ControllerContext controllerContext, ModelBindingContext bindingContext)
    {
        var actionName = controllerContext.RouteData.Values["action"] != null
                                 ? controllerContext.RouteData.Values["action"].ToString()
                                 : string.Empty;

        var attribute = controllerContext.Controller.GetType().GetMethods()
            .Where(x => x.Name == actionName)
            .Where(x => x.GetCustomAttributes(false).Any(a => a.GetType() == typeof(CustomActionFilterAttribute)))
            .Select(x => x.GetCustomAttributes(typeof(CustomActionFilterAttribute), false).FirstOrDefault())
            .FirstOrDefault() as CustomActionFilterAttribute;

        if(attribute != null && attribute.AnyProperty)
        {
            // Do what you want
        }
    }
}

By reflection I can find the attribute and use it in my modelbinder

Why not simply writing a custom model binder and work in the BindModel method?