Generally I hate these websites that lists these bookies and casinos, what they are actually doing is just to promote their referal links and the top 1 on their list is the one that pays the most for their affiliate program. That means these are just really unreliable to be the basis for someone really looking for a good sports book or casino. Though some are legitimately reviewing sites and recommending based on their true opinion, but more than half is what I described.
It is not true. This rating is based on global Internet traffic of websites by data Alexa.com, therefore it is fairly accurate, honest and progressive in comparison with other ratings. In simple words, the more visited website of the chosen bookmaker, and therefore more popular with the players themselves, the higher it is in the ranking in relation to its competitors.