I dunno about Sony, but the Sharp and Philips models I could find had thin bezels too. When you tile displays, you have two bezels touching, so the black line is at least twice as wide.
Zero bezel on 4 sides also seems to be noteworthy, because it removes some ways in which one could 'cheat'. For example the new iPhone. From what I understand the bezel on the sides and top could be zero instead of just really really narrow, but the bottom edge has the display electronics attached. To keep from having a big bezel at the bottom of the phone they folded the screen over, so the electronics sit behind the display instead of below. I'm not sure that allows true edge-to-edge display, so Samsung would have had to do some other trick instead of feeding signal in from the edges.
A wall display that can be tiled on three edges still allows for quite a big bigger displays (especially in situations where long linear ones are good, like balconies or the barriers in MLS fields), but not quite like this one.