Great link!
https://spin.atomicobject.com/2016/07/06/time-zones-offsets/

"Given a local time and an offset, you can know UTC time, but you do not know which time zone you’re in (because multiple timezones have the same offset)."

So, given a time zone you can know the offset (Google it, for example)..
Then, given the time zone and the local time, you can know UTC.
If orgmode gets the UTC there is not ambiguity.

But, that would mean that the offset related to the different time zones must be downloaded and updated from some site.
As you said before, that offset can change. For example, peninsular Spain has the same time as Berlin, but as this doesn't make much sense, it could change, so updates would be necessary.