Home Depot, we have a problem

Musing #3 More thoughts about taking things apart.  I took apart a new storm door latch last year.  There was nothing wrong with it but the reason I took it apart was that I had installed the whole door upside down.  I know, you’re wondering, how did you manage that?  Wasn't there a clue that it was going wrong.  It was one of those doors that can be left or right side opening.  I did all my figuring, but I drilled the holes on the wrong side of the door (fortunately not as critical an error as you might think), and installed the new (custom ordered I might add) full view door upside down.  You get pretty far into the process before it becomes clear it's upside down.  For this door it was when the door sweep wouldn't fit on the "bottom" of the door.  I believe this was the actual second to last step in the installation process.  The last step being to clean your new glass door. 
Since I'd never seen a door with the door sweep at the top, I knew I had a problem.  To mis-quote a famous movie, Home Depot, we have a problem. 
So I take it all apart, pretty much start over.  When I was assembling the latch/lock/handle mechanism (almost the last step), I lost a little oddly shaped ring/washer/clamp inside the door.  I still remember what the part was called, the "D"ring.  No getting it out without removing the door (again) AND taking a hack saw to the bottom of the door.  What the heck, I put it all together to see how bad it would work.  No noticeable difference.  What was that ring for if it works great without it? 
It's been 2 years now and the door and latch still work fine.  I've decided the "D" ring was the self-destruct mechanism (D for Destruct) that I have suspected are in all devices.  We use to suspect the car makers of building in "planned obsolescence".  Well with the self destruct trigger (the "D" ring) now safely disabled, that door and latch will out live me.