If OpenBSD delivers the blob as part of their OS, they take moral responsibility for it (which, for good reasons, they don't want to take). On the other hand, you don't have to deliver a blob to support, say, a hard disk.
I agree 100% with the stance of not distributing blobs.
But you can put it on the user to provide it. A lot of linux distros have gone this route, if you want to boot debian on RPi you either need to create the FAT partition and put the blobs there yourself, or fetch a third-party image which includes them.
That's the mentality difference between mainstream GNU/Linux distributions (though Richard Stallman considers them as unethical and only endorses 100% free software distributions, such as Trisquel GNU/Linux (cf. [1])) and OpenBSD (for the OpenBSD mentality cf. [2]).
But you can put it on the user to provide it. A lot of linux distros have gone this route, if you want to boot debian on RPi you either need to create the FAT partition and put the blobs there yourself, or fetch a third-party image which includes them.