Indeed, the point difference isn't much among those teams. Only the top two teams, Real Madrid and Sevilla staying ahead. But the leaderboard race is also competitive between them. The point difference is 5, but Sevilla has played 1 match less than Real Madrid. The position will change after each weekly round and there will be notable changes in the leaderboard within next three to four rounds. 11th rank team Espanyol is also in that dense group.
Yes, you are right, Sevilla is the only one holding on to Real Madrid with dignity. But now the gap between the teams is 5 points, and the fact that Sevilla played 1 game less and can get closer to Real is only a theoretical possibility. Because this game still needs to be won. La Liga is a rather unpredictable championship and they can lose points in any match, so don't jump to conclusions.