You don't need a computer for Magic Jack either. It cost me $160 total for 7 years with voicemail and FAX capability...$1.90 / month.
It is fear of change that drives these $300 per month Internet/Cable Box/Phone prices
You can't move them.
Another reason for cable modem is that the modem/router is in the living room so I can put one large UPS on my NAS, Magic Jack and cable modem WiFi router in case of power outage. Power outages are rare where I live but I feel naked without Internet/phone. I use laptop computers as desktops...Connect to external monitor/keyboard/mouse via USB and USB-C Display Port. My monitor powers my laptop (charges battery) via USB-C port.