Gear had attribute limits so when you add said materia to piece of gear it'll tell you if you'll receive it all or not, for that materia you would of seen a red warning before attuning it to the armor letting you know that only "this much" would be added when melding said materia to the piece of gear.

This is done to prevent players from stacking attributes so one player won't just put STR into everything, instead they have to balance it out based on the cap of said attribute per piece of gear.