Disagree entirely, their playstyle is easily one of the best to watch. I suppose if the majority of the fanbase is brain-damaged and only understands headshots and aggression it's boring. With C9s playstyle, it's easy to understand but extremely difficult to stop, their T sides are the best in the scene and their CT sides are methodical. They don't gamble stack off of no information as many teams do now, their retakes are solid and Ax1le is a monster. The main aspect of their gameplay I would say they lack currently is big-stage game experience and it shows in-game in crucial rounds and series.
5 viewers lol you underestimate the C9 fanbase in the US and low support wouldn't matter much they face teams like Vitality and G2 who have massive fanbases, on top of all the people who only watch majors. It would be an interesting chess game if the major final was between Vitality and C9 certainly not boring in the slightest.