Storing UTC is not a silver bullet
This is the same as the alarm clock problem. When a user creates an event, what does that user _mean_? In the alarm clock example, what should happen if I've set my alarm clock 7am and then travel to a different time zone? In the conference event example, what should happen if the local time zone rules change, or daylight savings time comes into force? Did the event organiser print marketing materials that said "starts at 1000 UTC" or "starts at 10am" with a "in the local time zone" implication?Events generally need to be locked to _something_ - whether that is UTC or a local time zone depends on the application.The iCalendar standard (https://tools.ietf.org/html/rfc5545) generally gets this right.