Umm..there are always at least 5 good players in each tourney at the start, its just if they lose then they probably will end up not bothering and not be there in the end.
I do my best to participate in every system tourney, and im in the top 10 for all 3 cue sports, i cant speak for others though, but i certainly don't think people are afraid to play in the tournaments. There are a lot of people in www.myleague.com/147break with high rating who play lots of tournaments and risk losing their rating against anybody.