In Germany about 20 years ago people were still doing dial-up using a broadband (DSL) modem. The provider wouldn't give you a routing device but only a bare-bones giant modem. When still living with my parents I remember rolling off an ethernet cable across the apartment every night connecting my PC with the broadband modem and then invoking a bash script initiating a PPPoE (point-to-point over ethernet) dial up connection to the service provider. That was before WiFi and even before home routers were a thing. Probably back until 2002 or 2003.

Edit: This is how my first DSL modem (without routing facility) looked like: https://www.teltarif.de/arch/2009/kw27/10jahredsl-rueckblick...

I assume it was so they could share the connection among two computers