It's a bullshit argument. With time zones, in some countries it's perfectly acceptable to call at 7:30 AM, and in other countries that's way too early. How are

It's a bullshit argument. With time zones, in some countries it's perfectly acceptable to call at 7:30 AM, and in other countries that's way too early. How are you supposed to know? Maybe the person you're calling is an early bird, maybe they're a night owl. You want to call a business - maybe they're open on Sunday, maybe not. Who knows when an appropriate time to call is? Easy. Without time zones, you post the hours (UTC) when you're available. You refuse to answer the phone outside those hours. UTC makes this easy!