In a soccer game you might have noticed that the players spend most of the game running which raises their hear rate. In football half the players are sitting on the sideline (defense / offense) at any given time and even the players in the game spend most of the time waiting with just very short amounts of running. They get a lot more exercise during practices. Baseball involves even less physical activity.
The only football player I know who ever died on the field was Chuck Hughes back in 1971, I’ve seen several soccer players literally drop dead on the pitch.
Playing devil’s advocate here: Why aren’t we seeing basketball players dropping then?