Good aligned nations may, either intentionally or not, generate characters who see the demon-binding as weakening the barrier that separates the planes. These characters may take it upon themselves to solve the problem by slaying or banishing the demons.

Not all of the would-be exorcists would be good or good at it, causing the occasional demon to be released from its binding.

Temples which oppose demon summoning may encourage crusades.

Whatever form it takes, the rest of the world won't stand by looking as their rival gains an advantage.

Crusades lead by celestials, riots to burn any texts,(or practicioners,) of summoning, whole cities protected by gargantuan magic circles, or commonly available means to detect demons all come to mind. I'm sure many other possibilities exist, but it's certain the opposition wouldn't sit back and watch.