“Please educate me, because as you can see I am lost in understanding the value of seat angle.”
coupla reasons i can think of to bring up this subject.
first, you bring up road cyclists as an example. they don’t care what their seat angle is. yes. but they DO care (sometimes, depending on the fitter and system) about where they sit in an XY relation to the BB, by virtue of knee relative to pedal spindle. what this yields is almost always a seat position of 72-74 degrees. so while in practice seat angle doesn’t matter, we see that the range of usual seat angles narrows significantly. therefore, KOPS, or center of mass, or whatever the focus of one’s system for determining road saddle position, the resulting narrow range of seat angles is a notable observation. if a roadie was set up at, say, 68° of seat angle, this might cause the subject to question the process used to determine saddle position, even if the seat angle itself is not the proper focus of fit. if this applies to roadies, perhaps there is utility for triathletes as well.
further, if people actually do measure their seat angles on their tri bikes, and if a great number actually find that they’re riding at +/- 80°, or if they’re all riding at 74°, perhaps that will be valuable information for bike makers who’re only making 76° tri bikes at this point.
this would also be instructive to governing bodies around the world who might be slow in making front/center rules that allow for steeper bikes to be ridden in their safest geometric configurations. if 60% of us turn out to actually be riding around at 80°, why are front/center rules built to accommodate bikes ridden at 75° or shallower?
more, assuming you’re attentive to FIST principles, our armrest drop formula is seat angle specific. For example, at 80° of seat angle and 78cm of saddle height, the middle of the formula’s range is right about 14cm of drop. but at 76° of seat angle the middle of the range is about 11cm of drop. no, the formula is absolutely not to be followed as a first principle. it is only a double-check on proper fit work already accomplished.
however…
if you’ve got 11cm of drop at 80° at 78cm of saddle height, that’s perhaps an indication that your armrests might be higher than optimal. while it’s hard-to-impossible to measure your own hip angle while in the aero position, you can measure these points in space as represented on your bike. i’d guess that 80° of seat angle, 78cm of saddle height, and 11cm of drop means a hip angle at bottom dead center of perhaps upwards of 110° (measuring FIST points) and this is likely a position that doesn’t adequately recruit gluteals (perhaps CK can comment on this).
assuming a slowtwitch reader fits the description above, he perhaps calls paul levine and schedules a fit 
off the top of my head, these are reasons why seat angle education might have utility. otherwise, yes, your thesis is absolutely correct.
Sorry Paul L, I had to put that in there.