By keeping fingernails short there is less of a groove to catch stuff and also it is easier to keep fingers clean. Long fingernails also break easily, leaving a painful, bloody and messy wound. You remember those horror movies where people are tortured by having splinters poked under their fingernails. Broken nails also leave ragged edges that are so annoying that you bite at them. Then the crud under the cracked fingernail gets into your mouth and gives you a cold.
False fingernails are worse.
They leave even more space underneath to catch dirt and crud. They also catch on things and not so much break themselves but break the real fingernail underneath. When this was found out, the hospital banned long fingernails and artificial fingernails worn by employees. Paul referred listeners to the Hospital Epidemiology Journal. It may make it easier to keep matching stockings together but don't tie them together in knots when washing.