When "quick links" made their first appearances on the scene, chains were wider. 5 speed or 6 speed, I'm not certain.
However, as chains became narrower, the tolerances tightened up, and quick links became much more sensitive to dirt
getting into tight places and inhibiting the disassembly process.
I believe that the side plates have to be able to move slightly inward to properly align with the the grooves in the pins allowing for the collapse of the link. I can remember having to flush the link with solvent and compressed air in order clean things out so I could disassemble the link. Dirt was always the culprit.
The master link pliers enable you to apply much more pressure to move the pins toward each other and achieve the desired result.
Use them or suffer as the previous poster indicated. Or, use a chainbreak and replace pins whenever you break a chain.

Your choice.........