A nonexhaustive list of FaceTime alternatives: Skype, Facebook Messenger, Discord, Zoom, GoToMeeting, Google Hangouts, Cisco Webex, Microsoft Teams, Spike, ICQ, Tox, Viber, WhatsApp, Line, WeChat, Wire.
/shudder
I’d argue not, as long as users can still achieve the same goal in a different way, and it doesn’t worsen their quality of life.
For instance, in this context, the OP’s mother can still do a phone call, or agree to use a different software - which, by the way, is probably free.
The USA simply isn't a leading innovator in this regard.
Hell, even the different cellular carriers fail this definition because you can't use a Verizon sim card to access AT&T.
The Verizon/AT&T comparison is interesting; because it wasn't so long ago that phones were locked to carriers.
Regulation could and should pry open the private networks of large software companies to facilitate healthy competition.