Exactly. Herd masses of people in long lines going through security, makes an easy target. Same thing happened in 1972 at Lod (now David Ben Gurion) Airport, in Tel Aviv, when terrorists shot and killed 26.
You don’t even need to get near security. You can walk into any major airport in North America with numerous pieces of luggage and line up with hundreds of other people at the intitial check-in counter for your airline. No security check and usually no visible sign of any security officials. Just airline ticketing personnel and some porters. I’ve been in line at the Toronto airport when there would easily be 500 people lined up in an area 100 ft x 100 ft. It’s even worse lining up outside a major sporting event. Just think what a car bomb could do in front of the gates at the Meadowlands on game-day for the Giants.