I would say that the OP is right to some degree.
Especially Native Speakers from the UK are awful. Their accent is so complicated and out of this world, that I don't understand how some schools would like to hire them.
I would never in a million times do that. I would prefer a German Native, who studied the English language for several years over any other Native speaker.
Even most Canadiens and Americans abuse the English language with their terrible pronunciations.
But a well spoken American Native is of course better than a German Native. However the gap isn't that big and the grammer part most likely belongs to the German, if however the American didn't study his own mother-language.
PS: Can be applied to every Nation of course
not just Germans^^