Polygon provides different channels for real-time feeds, one of which is AM.* (per minute aggregate). It would save considerable resources if it was possible to subscribe to that channel, rather than all trades, and have real-time population of an aggregate database, rather than a tick database.
One reason to use polygon over ibkr is polygon does not restrict the number of symbols to which one can subscribe. So a typical use case is to subscribe to thousands of symbols which makes the relative resource requirements of consuming a tick channel vs an aggregate channel that much greater.