I was more expresssing scepticism about how useful they were as an ally, since they didn't end up being a great ally for the Germans. I think the Germans would have been better off, in sum, had the Italians remained neutral. That is essentially where they were after they surrendered in 1943.
The Germans would have been
much better of if the Italians had not invaded Greece in 1941. On the balance, the Nazi's probably benefited, overall, from having Italy as an ally from 1940-43. The defection of Italy hurt the Nazi cause.