Perhaps a true master would be able to condition a submissive in the behavior patterns he desires...so that there would be no question about "the final say."
I never have a preconcieved idea that I will go tftb on him...it does not mean I do not want to please him...we definately have a bdsm relationship with D/s spice (not slavery, just nature) and the D/s roles do change back and forth...in my life, I have met few folks who were effectively dominant all the time...titles aside, honestly, unless there is abject submission, by your definition wouldn't any idea a "slave" has, (aside from what the Master allows) be topping from the bottom???
Seems boring to me. No challenge. I mean, is it truly satifying to have a submissive with no spirit of their own? But hey, I know that's just me.
How can you say it is not sm if someone tfb and still comes out nicely bruised?