Collections make it easier to handle multiple feeds/cameras. You can apply settings, share, create playlists all based on a custom collection. Each collection also has it's own profile page, allowing viewers to easily browse all the feeds/cameras within a collection.
Some common uses for collections:
Apply the same brand or adjust profile options to all feeds in a collection in a single step.
Share the collection using a share link or via email, no need to set this per feed. In the future simply add new feeds and viewers are automatically granted access.
Setup a common profile page for a collection of feeds and direct viewers to.
Here is an example feed collection profile page, at the bottom you will see previews of related cameras/feeds that viewers can easily browse to.