They do what exactly?
Narrate other people's work.
Wait. What?
Listen in.
The audio is terrible for the first minute (I was in a café), then we're good. Hey, we're audio guys, I had to at least be in a quiet room although I didn't have my good microphone (duh).
You have audio. You probably have a book cover. You're all set. Using an online (and mostly free) tool called Headliner, you can easily...
It's just so easy. It's probably harder to not do it.
In a nutshell, the answer to Why Now? is because we can. Sure, microphones and book narrators have been around a long time. But...