Because blind pick is actually shit for anyone the ONLY reason it is the most played is because its faster to get into queue. If everyone played Normal Draft, queues one the smaller regions woudln't be shit.
http://na.leagueoflegends.com/en/news/game-updates/competitive/how-rank-2017-season
Normal Draft will be retired at the start of preseason for all regions except North America, Europe West, and Brazil. Our goal is to offer the fewest number of queues that give unique experiences (so we can keep queues healthy) while keeping disruption low, and in all regions except NA/EUW/BR, normal draft had very low participation. In an ideal world, we’d like to retire normal draft in all regions.
those regions in which it is being removed
in all regions except NA/EUW/BR, normal draft had very low participation
