Coincidentally, there are hundreds of sanctuaries between those two end points that aren’t on the line.
Haha I was thinking the same thing. But then I realized that these are all sites dedicated to the Archangel Michael, each built centuries apart from each other, thus with no obvious means of coordination.
As to the issue of this not really being a straight line since this is only a straight line on a Mercator projection, I don't have a globe so I can't be sure but to me it seems even on a sphere this might be a line, although an arc at any rate, still a continuous line from the first to the last. It wouldn't be a serpentine pattern in other words.
Even if the line on a globe isn't perfectly straight though, it's still amazing that on a Mercator projection it is a straight line. So there's that.