Is there a hard limit on listeners to MQTT topics?

The Google IoT Core Registry page will not allow me to add more than 10 topics to create pubsub listeners. It has been my experience that in order to listen to events from the device, one requires all three of (1) The pubsub topic, (2) a subscription to the topic, and (3) This same topic in the registry.

If that's the case, is it therefore not possible to create listeners to more than 10 topics? I know I can listen to all events on a single topic and filter...but the whole point of MQTT is to save resources by separating communication into individual topics. Is this a limitation of the GUI, or a hard limit of the system, or perhaps something that can be increased by paying for a higher tier of service?

As @LeeDanielCrocker also mentioned in the comments, it is a limitation to have maximum of 10 event notification configurations per registry for Cloud IOT Core which is also indicated in the official Cloud IOT Core Quotas Documentation. As of now, this quota cannot be increased.