The role of the conventions has changed dramatically over time, as such things are wont to do.
It used to be about choosing a candidate and a platform, but nowadays there are modern ways of doing that without getting all the party leaders into the same building together. More democratic ones too, since the rank-and-file voters get a meaningful role in the process now.
Nowadays the convention is really a tightly scripted campaign event designed to harness the power of mass media coverage to sell a party’s candidate and platform to the voters.
