Combat system is beyond saving.

[Sunhwapark]

NIN - DRG - BRD - MCH being the only comp anyone in PF allowed?

Definitely didn't experience that at all. Or do you mean Stormblood's expansion where they had the blunt/piercing/striking debuffs tacked onto different classes that pretty much locked those spots (for meta chasers, at least) ?

Cross world pf didn't exist at the time, smaller population and it was harder to get people in groups on PF for them to be so picky. You'd be more likely to run into more people that would block/kick the 'imposter' player for faking fight knowledge and constantly failing all of the mechanics, and most people got gated by mechanics anyway in pf - at least on Cerberus server, A11s was a giant wall by the end of the tier.

Anyway - OP is right, combat will not regain the things it has lost which makes everything very reliant on the success of encounters - if encounters end up being boring, well...