Texas Hold-em is more popular because it was played more, by more people in the past. The original games like draw, stud, knock, and others required at least 5 cards per player. At times, such as on cattle drives, there would be too many players and not enough cards in the deck to play these type games. The concept of community cards was therefore devised. In Omaha, where each player recieves 4 cards, it would still limit the number of players to 11. (12 x 4 = 48 + 5 = 53) Since Hold-em was the most played, it became the most popular of the two. The onset of the internet has closed the gap but Hold-em's grip on the lead will probably remain forever.