Fatigue - perceived impact on combat/outcomes

[Wiedrock]

When it comes to combat outcomes (in whatever way) I often see references to Fatigue of units.
Why is that?
Are those WitE1 or WitW leftovers where things may have worked differently?
Or something I am missing?
WitE2 we have this:

Hello,

The manual is great, but to my knowledge there's no single area that summarizes all the effects of fatigue on ground units (I'm excluding air units). So I'm posting a summary here. Please note any corrections or if I missed something. Some of these are redundant but I'm basically paraphrasing from manual.

The tl;dr is: fatigue has a negative impact on MP calculations, by reducing MP by average fatigue level of unit divided by ten (unless you pass a CPP test: die roll of 100 <= CPP), and also negatively impacts CV by 1/3 of fatigue level (as a %. So 100 fatigue = 33% CV reduction). There are other impacts but these two are the biggest.

1. Units take more fatigue moving into enemy hexes versus friendly controlled hexes (administrative movement).
2. Disrupted elements at end of a battle add extra fatigue.
3. CV is reduced by 1/3 of fatigue level
4. Rate of gain for fatigue is influenced by morale and supply level, as well as combat and terrain traversed
5. First winter rules (1 Dec to 31 Mar 42): ground elements can suffer increased fatigue in logistics phase if in blizzard hexes or hexes with snow level of 6 or more. Support elements less likely to take fatigue, infantry elements more likely.
6. Units which miss fatigue rolls can lose morale during logistic phase
7. Commanders impact fatigue rolls via their morale rating.
8. Fatigue negatively impacts unit construction values
9. Support squad elements impact the amount of fatigue added or removed from a unit during a turn (in logistics phase).
10. Support units can gain fatigue, as well.
11. Fatigue impacts MP. In MP calc, average fatigue level of each ground element in a unit is divided by ten. This resulting amount is then deducted from the MP calc. So 60 average fatigue would reduce MP by 6 (60/10). This fatigue MP reduction is canceled, however, if a unit passes a Combat Preparation Points die roll.
12. Isolated units that are low on supplies will suffer additional fatigue in logistics phase.
13. Fatigue impacts amount of retreat attrition taken (when a unit retreats or makes a displacement move).
14. General supplies are used to reduce fatigue in ground elements during logistics phase.