I'm sure it is well-intentioned to create different 'two weapon fighting' feats that can be taken variably by fighters, rangers, rogues, etc, because each one has its own fiddly math-iness to ensure no build is better than any other build by too much of a margin.
Here's my relevant post from the other thread:
A Ranger at mid level can have an attack modifier of 0, -2, -3, -4, or more and that's only depending on his own gear and action choices (not any external factors, of which there are nearly always some). Then you roll heapfuls of dice for every attack, and you modify many of them with weaknesses and resistances.
So. Anyone's basic attack modifier is 0, -5, -10 if you spend your round doing three attacks. This is reminiscent of "BAB" from d20 if you remember. (And as you probably know, D&D 5E ignores this and just lets you do each attack at your normal attack bonus)
Agile weapons get a special "one less" modifier, so this becomes 0, -4, -8. So far, so good.
Now Rangers get 0, -3, -6 against targets that they have previously marked. If Rangers use agile weapons we get 0, -2, -4.
Now then, all heroes get to choose from class-specific feats and the Ranger can choose
"Twin Takedown" which allows him to attack with both weapons with a single action assuming he wields one weapon in each hand. There is also a feat called
"Dual strike" that pretty much does the same thing, just with completely different specifics. For one thing, it requires two actions, not just one. (Rangers access this feat through multiclassing or archetypes)
Our level 11 Ranger has both these feats. He also has three weapons: one throwing dagger which carries all the magical runes, one hatchet, and one cold iron bastard sword. The dagger and hatchet are agile, the sword is not.
This immediately makes the combinatorics explode.
He can start off a turn making a dagger/hatchet twin takedown attack, with 0, -2 attack modifiers (assuming the target is previously marked). He can then make a dual strike (with the same weapons) with his second action, and the attack penalties are -4, -4 for those attacks. If he takes these two actions in reverse order, we get 0, 0, -4, -4, so that's better (and different). Obviously the damage will be different for each weapon.
Okay so lets do Dual Strike before Twin Takedown in the future.
Now imagine he's attacking with dagger/sword instead of dagger/hatchet. The penalties become 0, -2 followed by -4, -8. Wait, what? The dual strike feat (but not the twin takedown feat) specifies that if the second attack is not made by an agile weapon, there's an additional -2 penalty. This explains why the first pair of attack modifiers are 0/-2 instead of the expected 0/0. For the second pair of attack modifiers the extra penalties comes from both this and how the third attack carries a "double -3" penalty for a non-agile attack (again assuming a ranger with a marked target, otherwise we're talking -10) explaining the -8. The -4 is the double -2 penalty for an agile weapon.
Okay so let's instead do the sword attack before the dagger in each pairing. Dual strike sword/dagger, twin takedown sword/dagger becomes 0, 0, -6, -4. Note how the numbers are completely different. (In fact, if you aren't a PF2 rules expert, I don't expect you to be able to follow along. Just go "this sounds extremely fiddly" and that's all I ask of you) Finally we have arrived at the optimal sequence.
That is just a single very small example. It just scratches the surface of what a single hero has to deal with for each and every combat turn, since the specifics rarely stay the same.