The dipole surround era ended because it was not scientifically sound

Evidence

All considered it is evident that this misadventure was not the result of applied science. Dolby ProLogic has been replaced by digital discrete systems. Two of the strong proponents of dipole surrounds back in the day still manufacture loudspeakers and there are no dipole surrounds in their offerings, just forward-firing designs and bipoles. End of story. — Toole, Floyd E, Sound reproduction- the acoustics and…, 831

Categorization

• ADDENDUM: A neat closing case study for the reader’s interest in how technical claims get adopted (THX licensing) and abandoned - parallels how sound-field assumptions break in small rooms.