I also wish to know the answer, unfortunately bitbook took away esports too - only reason I can think of is some of the matches are predictable but that doesn't make sense considering that is the same for other sports too surely.
I don't think predictable would be a problem. On the other hand, if the matches are unpredictable enough that they have trouble getting the odds right, they could be losing money on it. Either that or just not enough of a following to make it worth their time. Too bad, I finally had something "productive" to do with my BTC.