What NMs are you talking about for end game that REQUIRE zerging?
Its not required, only that faster kills = easier and safer wins. This in turn leads players to seek the faster method as that's the path of least resistance.
Then I outlined why this is true, that difficulty in FFXI is just dice rolls and by lower the number of dice rolls the enemy gets you dramatically lower the chance of something bad happening. "Strategy" is mostly about which buffs to use, how to program your character automation (lua/react/ect) and occasionally coordinating something special like bard swaps or which thing to hit.
That's pitiful by any standard.
Now to compare I'll use a raid I just did the other night called the Curse of Strahd. This is a super short synopsis. It's for twelve people and you need one tank and one healer, everyone is expected to be capable of taking care of themselves for short periods of time and brings their own meds or remove status ailments.
Everyone gathers at start and enters raid, there are three items that must be taken, the Sunsword, the Icon of Ravenloft and Holy Symbol of Ravenkind. The first NPC will pull cards from a deck and the players must write down the order that the five cards are pulled (M D B H I for example)
Go in first room, kill trash, focus kill 3 Greater Shadows of Hate that have a stacking on-hit effect of reducing your max HP, curse potions remove this. After their dead, split up and search out smaller shadows of hate while tank goes into sergei's room and activates Strahd. After the shadows are dead and Strahd is finished his monologue exit to the starting room and tank to the NPC. The NPC will open a door to the tower and the real raid begins.
The tower is covered in traps with only a narrow ledge that can be walked on, a character with trap skills must go forward and disarm them while the rest of the fights the constantly re-spawning mobs. Every 30s someone will randomly be inflicted with "Grip of Strahd", it's a 15s terror (ffxi speak) effect that kills them upon expiring. When this happens one of the people carrying the Holy Symbol or Icon need to use their item to remove the Grip, these items recharge every 30s. Upon safely reaching the top the first fight against Strahd starts. Inside Strahd will summon trash mobs and randomly put down several blue circles, get out of the circles or take a few thousand damage. Trash mobs will overwhelm the group if not kept down. After causing Strahd to run away you leave his room and the tank stays to hold Strahd (he'll reappear in next area) while the rest use dimension door back to the start, use rest shrine, and get ready for doors.
In doors the players split up so that one person is in each of the ten clusters of doors
map while the tank waits for the signal. Once the signal is given the tank exits the tower causing Strahd to spawn and the doors to unlock, each player must now check their four doors looking for torches labeled with the names from the cards, upon finding one they call out it's name and location (M 8.1) and check all their other doors. Once all are found the players need to hit them in the sequence given at the start. During this time tons of trash mobs will spawn and start swarming the players, hitting the fifth correct torch cause's the trash to despawn. After all touches are lit players gather at entrance to final room.
After resting and buffs, players enter the final fight that has Strahd and his three brides. Strahd starts out invincible but hitting him with the Sunsword makes him vulnerable for a short period, thus a melee needs to nerf their DPS to keep him vulnerable, for us it's usually the tank. Work Strahd's HP down to about 5~10%, then disengage and work all three of his brides HP's down to similar levels, if one is killed it will respawn at full health. Cause Strahd's HP to hit 0, then immediately kill all three brides, then the person carrying the Sunsword plunges it into his chest and you win the raid. If these aren't done in order, Strahd regens back to 25% and the brides are all back at 100%. Lots of circles and red mist to avoid as they are all instant death to any non-tank character.
And that is one of the more straight forward raids, Tempest Shrine and Fire on the Mountain are more complicated, Temple of the Deathwyrm gives people nightmares. This is just a good example of one requiring teamwork, communication, division of roles and a general amount of utility.