That's likely true, since DC motors need either permanent magnets or energy-wasting field coils. But motors are only a part of the energy-usage picture.
Ideally, we'd distribute "last mile" power as DC, and devices that really need AC would handle the conversion themselves. For instance, a polyphase inverter that's designed to drive a specific motor would be more efficient than a general-purpose single-phase inverter of the sort being discussed here. So even motor-drive applications could still be a net win for DC distribution.
Ideally, we'd distribute "last mile" power as DC, and devices that really need AC would handle the conversion themselves. For instance, a polyphase inverter that's designed to drive a specific motor would be more efficient than a general-purpose single-phase inverter of the sort being discussed here. So even motor-drive applications could still be a net win for DC distribution.