One study found that moderate ambient noise, roughly the level of a busy coffee shop, supports creative thinking better than dead silence does. A room that's too quiet can actually let your mind wander, while a room that's too loud just breaks focus outright.
The noise in a coffee shop isn't speech you're trying to follow, it's mostly a meaningless layer of sound. Your brain doesn't try to listen to it, it just processes it as texture in the background, and that light stimulation is what triggers focus.
You can get the same effect at home, a steady layer of sound similar to that coffee shop hum is enough. The goal was never total silence, it's that middle zone that doesn't distract you but doesn't leave you floating in emptiness either.