For flexibility of routing, a console needs channels.
These channels should not always be tied to a track, or a group.
Both the FX and Group Channels do not allow you to choose their inputs.
This may be convenient for most users, but it’s limiting for advanced use.
If you do not want to make the input on these channels selectable, I suggest you simply add a channel.
This is what in Pro Tools is called an Aux Channel.
It adds a lot of flexibility which for some users like me, is paramount.