Why is sliced cheese a thing?

Whilst making myself a cheese sandwich, I paused for a moment and examined a single slice of cheese wrapped in plastic. I unwrapped it and placed the cheese slice on the sliced bread, then I proceeded towards the bin in order to dispose the plastic cover and glanced at 50 other individual pieces of sliced cheese covered with the same amount of single-use plastic. 

Why?

At what point did humanity wake up in the morning and felt "damn it, I didn't cut a proper slice of cheese, I wish we had something for it" and at what point did it become a norm?

It's just so...unnecessary.