fabric scissors need to be sharp to do their job effectively.

cutting other things, even paper, can (and will) dull the blades enough so they’re no longer suitable for their original intended task.

then when gramma, or whoever, wants to use ‘their scissors’ to cut some fabric, and they aren’t functioning properly… let’s just say it may not go well for the guilty party.

tl;dr: they’re no longer pure and must be replaced with new virgin scissors.