I’m pretty sure they don’t mean “give up on time zones” but “express your timezone in UTC”. For example, central Europe is UTC+1. Makes almost no difference in everyday life, only when you tell someone in another zone your time. The idea is to have one common reference point and do the calculation immediately when someone gives you their UTC zone. For example, if you use pacific time and tell me that, it means nothing to me, but if you say “UTC-8” I know exactly what time it is for you.