Also Italian here. The other issue with using "Lei" is everyone would sound like some overly formal grand parent or maybe a government official... it would be like people suddenly breaking into the royal "we" in english.
On this, there is a historical note: the equivalent form exists in Italian ("voi"), but fascist ideologues considered it an "anglophism" and severely forbid it (because of course anything from "perfidious Albion" had to be uprooted)...