I've seen variations... some are sawn to within a few inches of the bottom then split apart, a strip split off the center part of each of the quarters and then the "log" is reassembled with wire. Some are done in a similar manner but only by splitting. Some are drilled down the center with a large auger bit and then sawn. I saw a large one that had been plunge cut in the end to form a pocket for kindling. Some are sawn with the kerf worried wider and some just a chain width. I have to wonder if the later are done by opportunists who haven't actually used them as I agree that the saw kerfs alone don't allow for much in the way of kindling.That may have been it - I vaguely remember, now that yo mention it, "Swedish" being involved...
However - the cuts in these were awfully narrow to insert anything burnable in - no wider than a regular bar... is that usual?
This video shows several methods.