In positions like these, there are winning chances for the better side, however small. It makes sense to do the 50 moves. In Q vs. R+B the winning chances are very minimal for the queen, although there are a few cases where the R+B have winning chances. So although the most likely result is a draw, it's not at all a dead drawn position.
The same thing holds true for other pawnless endings like R+B vs. R which is very common, and has the most dangerous winning chances for the stronger side, or R+N vs. R, with less winning chances, but still quite tricky to play.
In these kinds of positions I would always go the full 50 moves before I let my opponent claim a draw, also because pawnless endings are generally more difficult do play for the defender than for the attacker.
From this position, I had the rook + bishop. I offered at least 5 draws, but my opponent refused to accept. I could understand if I had just a rook trying to go for it, but when I have a bishop to support that rook no way can he mate me. So he chased me around for another 50 moves making no progress until I got a draw.
What I'm saying is when your opponent has built a fortress, and you can not penatrate it, and you know you can't. Why do some ppl like to screw around for the next 50 or so moves when it is clearly a drawn position?
Is it considered poor sportsmanship or insulting to fight an additional 50 moves in a very clearly drawn position?