I really, really (really) don't want to be personal, be sure this question is in general.

About the question

Occasionally, you run into answers where the poster suggests to discuss further via email, Face-book or whatever channel outside AU. It seems a "nice" thing to do. OP, especially a newcomer, would not likely refuse the "personal" attention.
What really happens is that OP is isolated from community input. Possible misinformation is not corrected by a second opinion, to mention something, and even if a working solution is produced, it is of no value to the site.

An example

In this particular (now deleted) case, the answer is accompanied by a series of gloomy comments in which the answerer seems to fight with an imaginary enemy, which in itself creates a questionable impression (towards a new user!) of what we're doing here.

Worse in my opinion is that the poster openly asks OP to "neutralize" the downvote, done by, no doubt, evil people (not me btw, didn't even read the answer):

"Didn't I just explain my answers get downvoted for explaining things in plain english?".

Moreover, OP is dragged into an imaginary war that is not his:
"my annoyance at the cliquey nature of the users of this site whose disdain of people like you is so fierce that they downvote people like me for trying to help. Eventually I will get so fed up about this that I will be contacting the site operators and suggesting they target this sort of bigotry".

The absolute worst, and the main point of my question, is the final attempt to lead OP away from the site into a private session elsewhere. I really think this is harmfull. If someone has a problem on the current behaviour on this site, there is META where things can be discussed in the open. Isolating someone into his or her personal atmosphere is on the contrary of what we're trying to do here.

Why adding the context of this specific example?

In this case, the suggestion to step outside the scope of AU is done as a final step in a questionable atmosphere. It is relevant in the discussion, since the answer to the question may not be the same in other situations, and driven by other intentions. If so, what would be the conditions that make a step into private spaces acceptable?