Fighters strengths should be somewhat countered by their lack of saving throw proficiencies and commonly low wis and int. So you can neutralize the fighter with enchantments and illusions, but I don't see that happening very often in the game. The AI priorities in terms of picking the most appropriate action and target to eliminate the largest threat seem a bit off.
That's because the game showers you with "+2 to saving throws" and "advantage on charisma, intelligence, and wisdom saving throws" gear.
You then have the githyanki racial gear tailored for fighters and eldritch knights also giving a ton of resistance to intelligence, wisdom, and charisma saving throws as well.
By the latter half of the game your characters are actually pretty immune to secondary effects. You can have a character cast well stuffed for immunity to frightened/charm, and then your othwer casters can apply Freedom of Movement for immunity to paralysis and restrain and your characters basically can't be CC'd outside the stun condition.
On top of that, most checks are dexterity and constitution saving throws, so martials are even more favored over casters because martial classes have way more gear that increases their dexterity as well as constitution.
The only example you see above is the famous spellmight gloves from the Dribbles clown quest having a ridiculously strong interaction with magic missiles and Stratagem form the Ramazith Tower scroll for Wizards. But Monks and Fighters are putting out similar damage and with way more magic items to allow them to do so, Fighters can put out dumb damage way before the end of Act 3 whereas casters only get the Spellmight gloves basically at the end of the game. That video showing the 25 AC wizard is also misleading because he's got the Raphael heavy armor equipped, basically the secret endboss item.
Martial classes are just miles ahead of any other classes for the vast majority of the game until late Act 3 where the spellmight gloves let wizards/sorcs/warlocks compete. And clerics/druid/rangers are still trash tier classes for damage. At least cleric has OP support spells and items plus Bless. But druid and ranger are the worst classes in the game, though Bards are close but Bards have Otto's irresistible dance which is among the strongest spells in the game.
