When I was a kid, I learnt at school that 'piuttosto che' was used as follows
"Piuttosto che venire con voi me ne sto a casa",
whose meaning was 'instead of', a contrast between two mutual excluding items.
Over time my feeling is that the meaning was changing and the expression 'piuttosto che' took the meaning of 'oppure', in the inclusive sense of the conjunction (inclusive or, meaning one or the other, but also both of the items).
So in this sense it is nowadays very common to hear things like
"Essi si trovano a Roma piuttosto che a Milano",
where the meaning would be "they go to Rome or to Milan or to both of the cities".
I personally do not like this usage and my idea is that it seems to be an import/export operation from the English language. Indeed 'rather than' translation is 'anziché', but the direct translation is 'piuttosto che', now used also in Italian with the meaning of 'anziché' ('oppure').
My question is: Is this usage theory supported in some way?