Please note the last sentence of what you quoted.
When Israel sends warning of hitting a weapons depot Hamas is known to force the people to stay at ground zero and get killed. The only people Hamas would allow to use the crossings would be terrorists.
Bullshit.
But let's suppose that it's true. It would be an even better reason to open up the crossings. If everyone coming through is a terrorist or working for terrorists, that makes it super easy to identify, surveil, and arrest them. Israel could absolutely cripple Hamas using your technique.
By Jove, I think you've got it!