It’s easy to dismiss a theory out-of-hand, if one is motivated to do so. But if you’re trying to solve a mystery, the goal is to come up with an explanation that fits the data. The point of this article is to point out that Langewiesche’s claim to have solved the mystery depends upon evidence which doesn’t exist, and requires overlooking evidence that does exist.

You point out, as others have before you, that a northern flight path requires overflying numerous countries. You, like others before you, assume without investigating the matter that this would necessitate flying through active air defence radar coverage. Unlike you, I’ve taken the trouble to investigate whether this would actually be true. You can read the results here: http://jeffwise.net/2019/03/07/wouldnt-mh370-have-been-seen-by-radar-if-it-went-north/

As for MH17, we now know that it was operated by a trained, regular Russian army crew. Crew members of much missile systems are trained rigorously not to fire without a direct order from a superior officer. The operation was carried out under the auspices of Russian military intelligence, the GRU. The Russian military had a fully function air defence surveillance system in place at the time of the shootdown. The idea that the Russians didn’t know the identity of every plane in that airspace is far-fetched to say the least.