Complex sentence: It was decided by the founders of IDPA, which included some of the founders of IPSC, that IPSC competitions had gotten too far removed from the reality of defensive shooting situations, and had become simply "gun races," which were heavily dependent on equipment.
Split into simpler sentences: It was decided by the founders of IDPA, which included some of the founders of IPSC, that IPSC competitions had become too far removed from the reality of defensive shooting situations. The IDPA founders believed that IPSC had become "gun races," which were heavily dependent on equipment.