Why can't I link contacts? (Moto G Stylus)
In the meantime, I have found out that the dialer of this phone really can't link contacts. What a bummer... I thought this was a basic functionality of all but the most basic phones. (Well, maybe it is, and this phone is just one of the most basic ones.)
In any case, be prepared to add a 3rd party dialer to the bill if you're thinking of buying this phone from anywhere but Verizon.
From Motorola:

The :Link&quot; feature that you've mentioned is only available for Verizon specific phones, so a Moto G Stylus that is purchased from Verizon would work with that feature.