So far as I can tell, I can't move individual, on-topic posts back onto the original thread.  Tony, if you can do that, it would be good to move a few of the more recent posts back.

Jacob,

I can hardly argue with any of that, but I don't think that it applies very well to run-of-the-mill scholastic players, aged 5-11.  These are the students that I have and that I imagine Robert Snyder has in L.A., not highly gifted chess kids whose parents seek out titled players for formal instruction.  

I volunteer at a local elementary school and offer a one-hour "Chess Club" once a week to all comers who "know the moves."  We have about 40 kids who come on that basis.  I also volunteer one evening each week to run "Chess Team" for a group of 10 or so of the more talented and bloodthirsty kids that I select from Chess Club, who also play in weekend scholastic tournaments.  Once I was lucky enough to have three kids rated over 1200 (we finished 3rd at the K-5 Nationals that year), but in some years I am lucky to have anyone rated 1000. 

At Chess Club the kids mostly want to play chess. The most teaching I will do is a 5-minute mini-lesson, about the fine points of castling; or the en passant rule, which is quite mysterious to most of these kids; or the virtues of getting out one's pieces and getting castled; or why 1.a4 is not a very good first move; how to mate with K+Q, sometimes even how to mate with K+R.  

At Chess Team the lesson may be longer and more advanced, 15 minutes or so out of the 90 minutes we have each Tuesday evening.  This is where I will start to address good opening play, typically starting with the Fork Trick; the Fried Liver and how best to handle the black pieces against 4.Ng5 (a very typical scholastic Fried Liver game, by the way, goes 7.Nxf7 Kxf7 8.Qf3+ Ke8 9.Bxd5 Nd4 10.Qf7++).  Relatedly I will always give a short lesson on why Ng5 in general is not a good idea if the only threat is to give up two pieces for a rook and pawn on f7; why Bb5+ is often not so great if Black has ...c6, and similar.  That's the type of thing most of these kids need to learn.  I will expose these kids to a few key lines, such as the Scotch 4 Knights out to 7.Bd3 - neither this move nor 6.Nxc6 are obvious to players at this level.  And I will sketch out how play could continue.  But even there, we mostly just play chess.  In this context I really do not have the time to teach variations, nor do I think most Chess Team members would be very interested or would benefit from it if I did.  But in general I do want these kids to play 1.e4 and to answer it with 1...e5.  For one thing, it keeps us all on the same page, and for another, I believe that it best facilitates the open piece play that I want these kids to become familiar with.  And yes, if a Chess Team kid takes up 1...c5, I tell him to cut it out.  Last night I had to tell a third grader to stop playing 1.e3, not because it was a bad move, I said, but because 1.e4 is more ambitious.  The kid was playing 2.d3, 4.Be2, 5.Bd2, not because he has a solid chess style, but because he's freaking ignorant of how best to get his pieces out.

On occasion I have had a particularly promising player, and have offered him or her free weekly, one-hour lessons.  Only there, I think, does my experience begin to resemble the subject of your remarks here.  That is when I really do seriously start to teach some opening and endgame theory, but even so practically all we do is solve tactics.  My experience with this is limited to just three or four children, but only in one case did I have the problem that the parent was actively teaching systems that I didn't want the kid to bother with just yet.  I explained my reasoning and he cut it out.  For illustration's sake, one of my recommendations is 3.exd5 followed soon by c4 against the French, not because it is best, but because it leads to the kind of position I want these students to know how to play.  

As it happens, the handful of kids that received private lessons from me all became good tacticians and quite adept (for their age) at open piece play, which I consider to be fundamental to everything else in chess. I admit that I am a chess nobody and that I have no place to lecture a titled player, still less a highly respected chess author and teacher, but that is what I believe nonetheless.

So I will respectfully maintain my view that among scholastic players of the kind that I have been working with over the past 17 years, it is in general a good idea to encourage play into open positions and to discourage play into closed positions or into positions with a significant deficit of space or activity.  And further that with the vast majority of these children, it is a category mistake to ask about chess style.