I had a "duh?!" moment in a sewing class I took years ago when a woman asked where her shoulder point was. I was wondering the same thing. The answer was it's the place where you want your shoulder seam to intersect the sleeve. It was one of those moments where the lightbulb turns on. Have you ever gotten so caught up in some intermediate thing that you lost sight of the end goal? Ever since then, measurements have made a little more sense to me. I stopped using patterns with seam allowances after that. The pieces make more sense to me without them. I use a self-healing mat and a rotary cutter with a gauge when I cut my fabric, now, and I think less about body measurements and more about the finished garment measurements.
That said, I decided to get a body scan this fall. I was hoping to import the scan results into a 3D modeling program and see if I could drape fit myself in virtual reality. I was disappointed when I realized I would not have access to the 3D image file, but the disappointment was only slight. I have since found myself reaching for the comprehensive measurements every time I trace a pattern. I get out my measuring tape and start comparing the pattern to my measurements. Then I start tweaking. Now, like most people, I am not perfectly symmetrical. Also, there are bumps and bulges that I prefer to be my little secret. Shhh... don't tell anyone. Somewhere in all this, I have again lost sight of the end goal - flattering clothing! I am having another "duh?!" moment today as I hear the echo of Cynthia Guffey in my head saying "... you know, there are some things you don't want to fit..." I am thinking about my hip measurement which is constant from full hip through the thigh area. If I make the pattern match my measurements through this area, I will have a garment that hugs every curve, and my profile will have an S shape. Fine if that is what I want, but I always reject clothes in the fitting room that fit me too well below the hip. So why am I going through all this trouble to do the same thing to the ones I sew???