I think you misread my post Bookworm; I was actually trying to point out that the obstacle clearance on a precision approach can be so small that the altimeter error does become significant. Just because there are occasions when it isn't doesn't invalidate the principle.
Sadly also your comments about the altimeter reading for a go-around decision reflect a common ignorance about the margins being operated to. I used to find when teaching IR's for a living that an hour showing students the section of PANS-OPS dealing with obstacle clearance usually resulted in them wanting to go around several hundred feet higher
Perhaps you ought to do some reading.