It's something I've honestly never thought of before when swapping stems. It was always a case of "don't let the stem stick up far enough to see the min. insertion line and you're good". All of my past assumptions aside about what I thought the reasoning for that was, NOW I more than just know, I understand, which I feel is an important distinction. Something to be said for f**k around and find out.

Glad this helps. It's something I'll do from now on when I put an older bike together. It's so easy to check with the stem out and headset off. Two quick measurements and you can know beyond a shadow of a doubt that you're good to go or you're not.
Now that I think about it, I really need to check my commuter. The stem is installed correctly and it's even by the same brand (CODA stem on a Cannondale) but I recall it being rather short. Something I'll do in the coming weeks.

I think I've heard that name before. Current plan is to talk to Jeremy Sycip (Sycip Bicycles) since I've got a personal and professional connection, primarily through my brother, though I definitely appreciate the mention, it's always good to know my options and I'll keep them in mind.

Right!? I could have easily found myself in the hospital with that kind of failure. It's come up in conversation with friends more than once now that if it was going to fail, which it was, it happened in just about the most ideal conditions possible. Not only was it at low speed with no cars on flat ground with friends nearby but it was also an absolutely gorgeous, warm, sunny day.
When it happened, I wasn't even mad, angry, scared, maybe a tad spooked, I was mostly surprised. All I could do really was chuckle as we all looked at what happened.

There's a saying in the world of flying that came to mind during this and that was "Any landing you can walk away from is a good landing", which has been the mindset I've had. I walked away unhurt and that's what counts. The bike doesn't even need to be replaced, it can be fixed.