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.
Though funny enough, English has settled on the formal 'you' even when addressing peers.
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)...