I presume you would have no concerns at all about dobbing in a friend and having your statement plastered all over the net after no charges are brought against them, some however might find the situation somewhat awkward, embarrassing or even damaging to themselves.
Oh I don't know. The McCanns did not feel awkward, embarrassed or suffered any damage by telling their story about a open window , whooshing curtains jemmied shutter and abductor...they went straight on the defensive!
Dobbing in a friend ? I would do If they were harming their children absolutely!
No charges does not mean they are innocent.
It doesn’t have to be about friendship - it could prevent employees dobbing in their boses, petty criminals dobbing in a gang member or fellow criminal, etc etc.
As has been mentioned. Information can be relayed anonymously like the 'Brenda Layland file' composed by anonymous supporters and sent to SY- who chucked it.
Also gangstas can get new IDs etc. they can also 'dob in' anonymously as well.