Isn't it quite common for companies to provide quotes to reporters through spokespeople without putting the person's name on record?No. That's the whole point of having a spokesperson.
It's become more common recently since the rise of small media (blogs, Buzzfeed, etc...), but the big players hardly ever do it. Sometimes it's used for brevity. For example, an article written for radio might not name the person just to fit into a certain number of seconds. That article can then end up on the web site without being re-written by the web team. It's possible that's what happened here, since Bloomberg has a radio network.
The New York Times publishes a book explaining how things work within its organization. There's a chapter about un-named sources, and the significant hoops a reporter must go through in order to not use names.