I fail to see the "complaining" side in all of this. I interpreted the question as "what's the meaning behind 'm_'?". Until I read your comment, it didn't occur to me to see it in a complaining light, also because I imagine the question would have been worded differently in that case (e.g. "why m_ instead of <something_else>?").

And judging by other comments to the question, I wasn't alone, luckily.