On the contrary. Maybe if you're on a hardwired desktop, but for everything else it is incredibly accurate. You don't even need to have GPS in your device -- WiFi is plenty.
Did you allow permission for location? Because if you did, it kind of defeats the purpose of showing that disabling this permission helps obscure your location to websites.. On my desktop, it asked for permission, and when denied it threw up its hands and said that it had no idea where I was.
Smartphone, it want to use GPS. That's kind of cheating, isn't it?
It is, but it also shows just how much information people could leak if they casually dismiss any permissions prompting with "allow" (or even worse, have such permissions be granted by default.)
Try it: https://whereamirightnow.com/ It puts my laptop exactly where I am.