Exactly. Your experience does not have to be the same as mine, especially with overtly broad statements. It’s no different than someone saying “Don’t visit city $C. It sucks!”. I mean, it’s a _whole_ city, are you sure _all_ of it sucks? Maybe you were unlucky in your experiences and I don’t have to be.

Now, if you tell me “Don’t visit restaurant $R in city $C, I got food poisoning and the service was awful” then I will probably avoid that place.

It should really be “If you go to Oxford for graduate studies, in department $D, under professor $P then you will probably have a bad time for the following reasons…”