Supporting two frequency-ranges requires more "radio stuff" built-in...something that's difficult considering space in the casing is at premium. Since bandwidth throughput isn't an issue, they opted for the most commonly available frequency-range
Most iot devices do not support 5.0.
Smart thermostats
Lights
Switches
Scales
Cameras
Garmin watches.
All stock with 2.5
Apple is the only one that has supports for 5.0
Best Answer@MikeJ70 said it perfectly. The bandwidth just isn't required for such a device, so no need to make other sacrifices to include tech that serves little extra purpose.