Why are some of the Fathers uncomfortable with the terms, “mine and yours”?

St. Pachomius, the founder of Christian coenobitic monasticism, believes that these two words can ruin a monastery and the monastic life.

St. John Chrysostom says, “And observe, that concerning things that are common there is no contention, but all is peaceable. But when one attempts to possess himself of anything, to make it his own, then contention is introduced, as if nature herself were indignant, that when God brings us together in every way, we are eager to divide and separate ourselves by appropriating things, and by using those cold words mine and yours. Then there is contention and uneasiness. But where this is not, no strife or contention is bred.”¹¹¹¹