O.B. are cheap and easy, but have their drawbacks. Production of non-discrete imaging and a "smeared wall of sound" (the very opposite of the stereo premise). Lack of bass without box reinforcement. And they have a greater need for placement out into the room than other types of speakers.
A smeared wall of sound? A lack of bass? Seriously, have some coffee, that is absolute nonsense!
Really! I have owned numerous types of speakers over the years, Magneplanars, electrostats, horns, full range single drivers, stand mounts, floor standing boxes etc. My experience with OBs is when rightly set up they provided a huge sound stage with the most defined imaging that easily rivals that of any other type of speaker. OB bass is also superior to anything one can get out of a box, and it is not nearly as problematic or in need of room treatments as boxy bass, which also by comparison sounds artificial.
As for placement out into the room, any speaker - even corner horns - sound better when pulled out into the room. The more room a speaker has to breathe, the open and airy it will sound.