> Couldn't this be solved in the (IMHO) proper way; always using UTC,
> letting clients do the conversion?
Not really. Suppose the client is in a timezone which has daylight savings in effect and set a recurring calendar item. What should happen when daylight savings is turned off in Winter? The user set the meeting at a specific hour local time not UTC. You can make the client automatically split the recurrent meeting into two both in UTC, but that causes other problems. Server has to be timezone aware to handle these kinds of cases.