I'm late to this discussion, although have been following.
The transparency argument is an interesting one. In the eyes of brands, high profile bloggers and instagrammers have to a certain extent taken the place of previously coveted editorial space in newspaper supplements and glossy magazines.
Previously, Martinhal resorts or Bedruthan hotel would have courted travel journos at the Sunday supplements and lifestyle mags but are now equally (if not more) likely to offer freebie trips to bloggers and instagrammers than travel writers on the understanding there might be a favourable write up as a result.
This is still editorial, not advertising, IMO, so the #ad or #spon doesn't apply.
The only difference is that each blogger/instagrammer is making their own rules for editorial integrity whereas travel writers would have a policy to adhere to, dictated by their editor.
We (bloggers / instagrammers / followers / publics) are all figuring it out as we go along, and deciding what we like/don't like. There will be differences, of course.
The exposure of children on social media is a different discussion altogether. Personally, I'm becoming more cautious as my children get older. My eldest (8) definitely has an opinion over what she is comfortable with on fb and insta. It's very limited, and I respect that.
My youngest, who inspired me to start blogging, is severely disabled and unable to tell me his opinion. So I'm figuring it out along the way, raising awareness and campaigning to improve his and others' future, while aiming to protect his privacy as appropriately as I can.