I've thought about it. You are completely robbed of the feedback your skin gives. Audible and finger sensations is all you have to judge your engagement with the hairs. I'm sure it's easily learned with practice, but yeah--that first time or two has to be nerve-wracking.

Reminds me of the time my sister, who was in barber school at the time, cut my hair. It took 4x longer than a pro. That was before I started clipping it.