That imo is because SU-76/Stug main role is counter mediums tanks with a Pop of 10-14, M36/FF/SU-85 are meant to counter Heavy/Super heavy with a pop of above 20.
This is your personal ideal. Jackson and SU85 are the primary choice for all targets, and UKF has no "light TD" so you buy the FF to kill mediums as well.
Mainly because it is vehicle costing fuel and not infatry.
Cost has so far not been a point to influence population. This was a response to your claim that counters are always cheaper than what they counter, which is not true.
I am not sure how you compare strength between main lines and support weapons but if one uses cost as an indicator, HM-42 is 260 6 pop and grenadier is 240 7 pop.
Again this relates to both the "counter is cheaper" claim as well as the claim that the role influences the population. We see units of completely different roles costing the same population. Therefore the role is no predictor for population cost.
And one has to keep in mind that many units have seen changes in cost and power and pop was not always adjusted.
Not sure why you quote that as a counter to my point. The note says that population has been adjusted to the power level as well as to create a higher cost for spamming Grens because you can't fit as many other units into the build anymore. Which is exactly what I originally postulated.
Units can be balanced by both cost and power adjustments. Both have been extensively used in the past. High impact units get high population, low impact units get low pop.
As one can see Tiger was artificially "over populated" to reduce the power of building more than one.
In sort population role is imo a little more complicated.
Tiger has previously been high pop because the meta was to get two which created a huge power spike. The attempt was to counter that by high pop cost. Heavies got limited to one, power spike was lowered, population adjusted accordingly. Exactly what I initially claimed.
I have no idea where you are going with this thread. What I initially debated was your claim that the role of a unit influences the population cost, nothing else. Please refer to only this point then.