Re: That parents are actively interested in their children's lives
You are correct. It is something the writer wants to put stress on. Also, it fits neatly into one of those classic, and very commonly encountered, elements of English communication: what is sometimes called the "Rule of Three". This is where just about any list is always made up of three elements - with the final one having the most emphasis. It's the "Good, better, best" syndrome. In this case, it's "....is a positive thing. .....is also great. Nonetheless, experts insist that...". And you know that the writer wants to place most emphasis on parents not crossing boundaries.
Sorry, I can't help you on your BTW question.
I'm not a teacher of English, but I have spoken it for (almost) all of my life....