polar tulip
Compared to spawn rooms, for example, spawning in the open provides obscene visibility.
Compounding this, spawns are far back to justify the on-spawn speed boost and to let people full sprint to combat.
Spawns are generally centralized, as it's important to have a beeline to combat.
What does this mean for flanks? In 64p you'll see a spawn wave every 5-10 seconds. It takes about that long to cross any good flank if not longer. Falmire, for example, on the prisoners has a quite nice flank... split down the middle by one of the two spawn locations available to defense on that point. This heavily limits the meaningful ability to flank.
Similar themes exist on most points to a degree that it can even be a bit silly. On Lionspire, for example, the bridge-side spawns for defense on the courtyard intersect with the flank-side spawns for offense in front of a statue in front of the courtyard.
Why does this matter?
The constraint of archers is weakness in melee combat in exchange for a range which requires flanking to access. No flank, no weakness. This means the only way to balance archer is to nerf it until nobody will ever want to play archer ever again. That isn't ok, and it's the fault of the spawn system, not of archer itself.
Some objectives are particularly difficult because flanking doesn't work. Lionspire catapults, for example, are double-fucked by the beach one being in the desertion zone and the forward one being basically in line with spawn waves on top of having way too much health, making it borderline impossible for defense to properly shut down either catapult.
There are similar themes in other maps, but I think the point is made enough to be applied elsewhere.
Also, Ambusher just becomes better throwing axe skirmisher because why are you even trying to flank inside of spawn waves dummy.