They don't have to blow that fast. It can be regulated.

But yes, I've seen low-O2 installations also. These have other issues though, like no protection when humans need to be in there for maintenance. And the need to be very very careful when reducing it again, making sure everyone is out. It happened to my colleague once that this went wrong and while it's not low enough that you'll die, he wasn't exactly feeling great for the next few hours.