As I just said, originally it was never about accurately measuring the light output but a tool to aid the modder in getting more out of a budget light. A check point out of the box, and continuing check points along the way during the mod to ensure the work done produced viable results. EXACTLY how many lumens the light makes is really, in the end, irrelevant. All the variables knock the numbers down in a constantly descending curve anyway. Ball park figures, for the end user, are all that is truly necessary. Remember, the percentage of difference between the home built PVC P-Trap light box and the very expensive professional sphere are most of the time simply not visible to the eye anyway.
Measuring a side emitting low output tungsten light with the same equipment used to measure forward emitting LED light, apples and oranges. Science says light is light, of course, and Photography favors the golden hour, but what are all these millions of flashlights actually used for? Finding the keys dropped in the grass? Science application overkill. Using NASA grade equipment to go for a walk. And yes, I know, I could well have donated the funds required for me to play with all these flashlights the past five years… the incremental decension into a bad habit is rarely recognized as the wrong path.