That's an argument for different display formats, where UTC offsets aren't the worst thing in the world but actually you should just display whatever your users

That's an argument for different display formats, where UTC offsets aren't the worst thing in the world but actually you should just display whatever your users want, which will often just be a time with no TZ indication at all. For storage of future events, use a proper TZ entry, or suffer like Microsoft did when the US decided to change the date it started summer time and everyone's calendar entries were off by an hour for a couple of weeks.