I wouldn't be surprised if the damn antennas are just empty. They don't seem to serve any purpose.
It also compensates for interference dead spots when you hold your phone into such a spot.
The long sticks typically radiate in the plane normal to the stick, i.e., if you make them all perfectly vertical, they are focused to the same floor. Individual ones can be rotated readily to cover special spots, especially if you have more than 4 antenna.
I generally recommend just maximizing angles between them, i.e. 90° between 2 or 3 antennas. Wall attenuation & reflections will equalize it out, and you have a lower chance of dead zones. The ≥4th one —on the same radio— is YOLO. Annoyingly enough, for some devices they don't tell you which antenna is on which radio.
However, they also have more than 1 radio these days, and sharing the antennas on them not exactly beneficial; if you have one 2.4GHz, 5GHz and 6GHz radio each, you might as well optimize the antennas for each radio. And even if it's the same band, separate antennas allow you to have distinct radios cover distinct space with different RF propagation characteristics.
(They're not empty, or at least I haven't found any fake ones yet.)