Theres some scenarios I can think of. While I agree I would especially prefer for them to use the devices language settings here or some scenarios I can think of to possibly use the Geo Location.

1. Areas Where users know multiple languages and the translation doesnt really make as much sense. Users In the english speaking Toronto visiting the french Speaking Montreal. If a map app said stop instead of Arete a user may be looking for a stop sign rather than the french word of stop and may not be as sharp in the driving context. Or possibly trying to translate street names when theres no need.
2. If your using a top notch translation service and you only support a few languages and thus anyone not in those markets you default to your "other language". Ie if your describing interior design services and you paid for expert translation for german english and russian rather than throwing in a half baked algorithm attempted Chinese translation that people would know is of low quality you default to whatever one you think people will most likely know (maybe english) rather than users with their device settings in Chinese to think that your site was rushed or perceived to be of low quality. I know when I read sites or menus with terrible grammar and miss spelt words I think the quality will be less.

Those are just fringe cases on why you might do it. In general its a [bad idea], and your geolocation isn't always that accurate 1

Theres some scenarios I can think of. While I agree I would especially prefer for them to use the devices language settings here or some scenarios I can think of to possibly use the Geo Location.

1. Areas Where users know multiple languages and the translation doesnt really make as much sense. Users In the english speaking Toronto visiting the french Speaking Montreal. If a map app said stop instead of Arete a user may be looking for a stop sign rather than the french word of stop (Arete) and may not be as sharp in the driving context. Or possibly trying to translate street names when there is no need to do so.
2. If your using a top notch translation service and you only support a few languages and thus anyone not in those markets you default to your "other language". Ie if your describing interior design services and you paid for expert translation for german english and russian rather than throwing in a half baked algorithm attempted Chinese translation that people would know is of low quality you default to whatever one you think people will most likely know (maybe english) rather than users with their device settings in Chinese to think that your site was rushed or perceived to be of low quality. I know when I read sites or menus with terrible grammar and miss spelt words I think the quality will be less.

Those are just fringe cases on why you might do it. In general its a [bad idea], and your geolocation isn't always that accurate 1