Perhaps because they have one job and they cannot do it effectively, therefore there's no draw. But the Commander also has no late-game, and the Soviets have a weak late-game, meaning most people are going to grab a Commander that can grant them a late-game regardless of how good Partisans are.
Glad to see that you acknowledge that
In an ambush, yes. To use them effectively you have to keep one eye on them at all times so you see when an enemy is coming near them to manually begin the ambush before they get spotted. That's a heavy micro tax, which makes up for their low cost but does not justify their low effectiveness. If they can't ambush a default infantry unit and win, then they have failed at their only job.
What is that job that in your opinion have do and they can do?
Can infiltration commands do that job more cost efficiently?
You are simply expecting too much from 210 CP 1 unit.
If you actually have specifics stat and cost for your suggestion pls go ahead because this debate does not really lead anywhere.