Kathy Iandoli contributes a piece on the lost art of cratedigging, which you can read over at Medium:
So what’s the point, right? Well, there is a utility for cratedigging that dates back decades to the earliest days of hip-hop production, because records were the raw materials for hip-hop tracks. The art of sampling was awesome albeit arduous. A producer would find a “breakbeat” (an instrumental section or drumbeat) or a snippet of sound from a record that they liked; play the vinyl on a turntable; and record that piece of music onto a sampler or a sampling-enabled drum machine where it could be replayed and layered in conjunction with other sounds in the beatmaking process.
To acquire the vinyl, they would hunt. They raided record stores and hit record fairs in the early morning hours to scour through crates and crates of wax. The Roosevelt Hotel Record Convention on E. 45th Street in New York City was a big one. Dealers would gather and legends of hip-hop’s Golden Age would arrive and peel through the layers of vinyl to find what they needed.