[squeaky-clean]

The article isn't about implementing your own time zone handling directly. It's about incorrect assumptions you can make when using such a timezone database or library.

For example, carefully consider when events need to happen at a fixed time relative to server time (utc) vs user local time. Consider how you handle changes to the timezone database. A timezone change can cause the scheduled time of an event (such as billing) to not exist in that time zone, or for a scheduled time to occur twice. A user changing their timezone setting can cause a similar effect.