That's partially true. The push to "upgrade" police sidearms was prompted in no small part to the 1986 shoot out between the FBI and two bank robbers in Florida. The 10mm cartridge was developed at the behest of the FBI and led to the 40S&W which has become a very popular police and home defense caliber. The stats for police shootings puts the hit rate in the low double digits. Police engagements are high stress encounters under dynamic conditions. So it's not entirely surprising. The benefit isn't as much the large capacity magazine as it is a cartridge that provides better end terminal ballistics.