Content Finder works across worlds/servers.
People from different servers can not meet in the open world, but can only meet in instances (or perhaps more specifically within a dungeon).
So the only way for the entire party to assemble together is when they are in the same dungeon.
To ensure everyone is in the same dungeon they have to be teleported to the same dungeon.

It sounds like this is a side-effect of having cross-world content finder (or perhaps, a limitation of not having one server for everyone in the world, granted that may be too difficult to manage).

The plus side of course is, that people can more easily find others to do activities with.

The concern is that people within the same server (even LS/Company) will use this as a method to quickly teleport from place to place and never leave their guild halls.

It would be nice if it could restrict the teleport of people until the people are at the entrance of their respective dungeon. For example, if everyone was at the entrance of CC in their respective servers, then hit 'teleport' and then were teleported into the dungeon.