Wrong. You failed to read the words. Let me do that work for you:
Dolby knows that the majority of users will not install overhead speakers. In fact, the majority of Atmos users will be using sound bars, since today, sound bar sales dominate over AVR sales. If they forced overhead speakers, it would be a commercial failure. That's why HT Atmos is used for background sounds, atmospheric diffuse audio.
They support large number of discrete overhead speakers to make people with deep pockets feel like they can spend big bucks on a new high-tier system, and the AVR makers can sell $3000 units. However, HT Atmos is designed for the mass market, and if you listen to most content, including Dolby's own demo content, that is disconnect the bed channels, you'll find Atmos is used for non-localized background effects.
Simply put, overhead speakers is marketing for rich people.